Most Acer species are quite tolerant of black walnuts/juglone, Acer rubrum included. I'd have more concern about trying to establish any tree in close proximity to large, already well-established shade trees like the walnut. There will be just a lot of competition for soil nutrients and moisture and he with the most well-established root system (the walnut) tends to win :-) I'd start with a smaller tree (easier and faster to establish) and provide a lot of TLC for a couple of years, primarily in the form of regular, deep irrigation.

'October Glory' is arguably the most popular cultivar of red maple and is widely available - you shouldn't have any difficulty in locating one.

Thanks for the info gardengal48. Sorry it took so long to respond, had to leave town unexpectedly. I will most certainly use your advice.

From a visual standpoint a cluttered effect is produced when different kinds or sizes of trees are put near one another. Each is an accent point, with what is called a Sphere of Influence that extends well beyond the spread of its branches.