Two options for you to investigate. First, Mark Boyd has done a number of tours out of Asheville, and IIRC a couple of them went north to Kentucky. Check out http://www.cs.unca.edu/~boyd/bicycling.html
for his journals. (Note: from what I know of at least one of his routes, he may be nuts! U.S. 19 may have lost some traffic with the completion of I-26, but it's narrow, winding, and has too many drivers going too fast for my tastes.)
Second, although this is a bit longer and involves doubling back a bit, stay on the TransAm through Damascus. From there, figure out a way to get down to the Blue Ridge Parkway, and follow that into Asheville. You could either take the Virginia Creeper all the way up to Whitetop, then cut down through West Jefferson, NC, or go down from Konnarock to Troutdale, and cut through Mouth of Wilson on 58 and over towards Sparta.