Hi Ross. First, I hope you keep your Geranium going, especially because of its memories.
45 years is a long time keeping a geranium, or any plant for that matter.
I'd love seeing a pic of the entire plant..

It's hard determining sizes by pics. The Walmart pot looks gigantic. What's its size? Measure the diamter..
Also how long/wide is the pot it's in now?
You don't want to overpot. Geraniums are similar to succulents: they need well-draining soil, a good amount of sun. They don't like sitting in water..If your new pot is too big, your geranium will be sitting in excess soil and if it's overwatered, chances are root rot.
Pot according to root size.
Now that winter's coming, days are shorting, growth will show down. Many ppl root/repot during spring when plants start putting out growth, since geraniums root fairly easy, rooting can be donw throughout the years. Give it a try.
If it was my geranium, I'd take cuttings of the longest branch. Cut into 4" pieces and root. It can be done in the same pot as the mom or in small 4" containers.
Last winter my puppy broke a piece of geranium. I hate tossing cuttings, so stuck the broken piece in a 4" pot and watered..it rooted and now stands about 1'..Didn't even use rooting hormone. It was funny too, because here was a broken piece of stem, (at the time about 5") and it bloomed a month or so later, in mid-February.
Anyway Ross, please measure the new and old pots. Good luck, Toni

Ross, you have inherited a plant that has not lately been given sufficient sun....the one long limb (or branch) is way over what the other part of the plant has done.

First, you should, before you do anything, learn about why plants should be transplanted into different sized pots and why you should not go up more than one size at any one time.

But, consider this: you are 6 feet tall, weigh 200 lbs.
You eat usually an average meal including meat and potatoes, vegetables and dessert. You eat only what you feel you wish to at any one meal, then you push yourself away from the table to relax and digest what yuo just ate.

Consider another possible way of enjoying your dinner.
You sit down and the meal is placed in front of you. You eat it...and are satisfied and attempt to push away from the table. Ugh, ugh, you have to sit there and eat another....then another, then another....then another...
you get the idea.
That is what you would be doing to your plant if you put it into a container too large for the roots to properly take noourishment from. The roots cant push themselves away...they extend outward in the large mass of soil where they continue to absorb nutrients....and water.
If the soil mass is very large, they soon are unable to take up more....they lose this ability and even when they are hungry, are not able to drink or eat.

Hence the reason why plants are suggested/recommended to be given new sized pots only one size up until such time they have outgrown that...and need a further one size up.
They are able to absorb the nutrients from as much asoil as the roots allow...and no more.

You don't say just where you live; if you experience cold winters. I suspect you live in a warmer clime, hence the reason why the plant has reached such an age.
For such a plant you certainly don't want to do something drastic. One of the easiest methods of securing a plant is by taking cuttings from the mother plant.
I suggest you do this. Take many cuttings as the plant allows while still protecting the mother plant as a viable growing geranium.
Geraniums, when cuttings are taken, usually devlop roots within 10 days to two weeks.

Geraniums over-wintered. cuttings:
snip the cutting at 3" long and put on a sunny window sill. Let them stay for two days there to harden off. Then, dip the cutting into a "root hormone" (either powder or gel) and put them into a mixture of sand and vermiculite. Water well and it will develop roots.
Transplanting to a container (pot) later or put them directly outdoors.

Only take cuttings from healthy plants. If any part is sickly, you are best to cut it out and not use for cuttings.

If you live in a northern zone there is another method of wintering the entire plant but certain requiremesnts must be met.

Geranium is a very easy plant to divide if you wished to separate it into two or more plants. This can depend on just how good a health is the plant and its roots.

Hello Jeannie and Toni, thank you for the response and im sorry I took so long to reply. I have been super busy lately and I did check up the other day, lol, but I was so tired it sounded like you guys just wanted me to chop up all my plants into lil 4" pieces

. . . now that I have read them a few times I think I got the wrong pot.

what they are in now (after doing math) is a 11 quart

and the new big pot is a 65 quart which is probably way, way overkill.

also I live in northern Illinois

so . . . should I go ahead and cut off all but like 1' of the branches and let the plant heal for a bit before transplanting? . . . meanwhile work with the trimmings of what I cut off??

also cant you just stick it them in water until it roots enough and then plant it in dirt?

I guess it is getting a bit late in the summer season, and im not sure if I dont think it wouldnt be a bad idea if maybe I just trimmed them and played with the starts and did the transplant next spring?

also what brand name of root hormone is the best for the money??

thanks kids!!!