Every build I do I say to myself; this engine should really take advantage of a roller cam's technology and blah blah... Then I actually price one. In terms of return for your dollar its not really worth it. I actually had a tech at Comp Cams talk me OUT of buying one. In truth, until you buy the cam, the retro rollers, pushrods, bronze distributor gear, thrust bearing, and all the other associated goodies it can be $1200 or more just in parts. That's a huge cost for another 20 hp.
If you want to do a roller engine and save a ton of money, just find an 87 or newer 350 core that is already a roller block and swap your new parts to that block. I think you'll find that since the newer core engine already has all those parts (and the cam and lifters are cheaper) that you'll save tons of money doing it that way.