Tough call. You're right, the 17-inch riser will give you a 62-inch bow with long limbs, 19-inch riser will give you a 64-inch bow with longs. The question is, do you need limbs that long?
Let your draw length decide. I think a 60-inch recurve is about optimal for a 28-inch draw, 62 for 29 inches and 64 for 30 inches. Of course, folks with long draw lengths shoot shorter bows, and folks with shorter draw lengths shoot longer bows, but I think these are some pretty good parameters.
Both risers will let you build shorter bows with medium and short limbs. 15-inch and 17-inch risers seem to be popular hunting lengths, with some preferring 13-inch or 19-inch risers. The sight window does get pretty short on a 13- and even 15-inch riser. Will have plenty of sight window length for vertical bow shooting with 17 or 19-inch risers.
If it were me, I'd go with the 17-inch riser and medium limbs to make a 60-inch bow for my 28-inch draw. That's the length I shoot for hunting and 3-D. It's a personal choice though. Go with what you like.
Anything Bob makes/offers is top quality. Good luck.