I run this in my 68 350 and like it: http://www.summitracing.com/nv/parts/sum-2801. I also have the #17 heads, Performer intake, 1.52 roller rockers, and Hedman shorty headers (for ground clearance) and full Flowmaster exhaust with H-Pipe. Bowtie Overdrives level three 200-4r tranny with 2400 stall, 8.5" 4.10 posi rear (2200 rpm at 70 mph...not bad).
Old thread from "back in the day" (and before I put in the 8.5" 4.10 posi rear):
