First off, I think you should get at least 1 of each!!! Having said that, I have a 32" draw length (actual and not embellished..when I do what I'm supposed to) and choose to shoot a 58" Thunderchild, 60" mountain monarch, 62" Desert BIgHorn, or a 64" buffalo.
Yes, I can build you a 68" buffalo, but I believe it to be an albatross. I have built maybe 4 and loathed building them. Didn't care to shoot them and prayed I made weight or I would likely still own them.
If a 64" or 66" isn't smooth enough, drop a few lbs off of the draw weight and they will feel as smooth as butter. This is the case with most every bow out there that is long enough for your draw length. The buffalo is not a "D" style bow. At 68"s you will loose speed even with a 32" draw length.
Thanks, BigJim