What a conundrum. I would go with the plant's already established tendency and plant it "upside down" with the shoot for this year aiming skyward, the old stem downward, providing the shoot has a clear pathway through the tubers. Any other eyes that form and grow should find their way to heat and light from their upside down state.

I hope someone else chimes in. I've killed more bulbs in one lifetime by planting them wrong than should be legally allowed!

Plant them with the new shoot growing upwards- if you plant it down it will try to go up & take longer to get to the surface- they do go for the surface sooner or later but if you have very heavy soil they'll take forever to get there.
Cut off the old stalk as short as you can without damaging the new ones or the tubers. If they're like most bagged tubers that you get at the nursery, there's a lot of broken necks & damaged tubers anyway & you can just prune them off & start with a nice clean, viable tuber with it's new shoot going upwards.