The most popular (in my experience) is the 1776cc. If you choose this size, I would also use a 69mm (stock size) counterweighted crank, 041 or 042 heads w/single high-performance springs, a 110 or 115 cam, stock rocker ratios, chromoly pushrods, case savers with 10mm head studs, and one (single, not dual) 40mm Weber carburetor. I would also suggest a Bosch 009 distributor with a Pertronix electronic ignition module. Since you have a '74 Super tranny, I don't believe you will need a "freeway flyer" unless you're looking to cruise at higher than about 85 mph. You can use your stock one. My stock late model tranny in my '63 beetle (yes it is not the original) allowed me to top out at 115 mph at about 5000 rpm. I wouldn't suggest doing that for a prolonged period
. At 85-90 mph it ran smoothly and easily. Anyway, this setup will make you very happy if you want some extra horses and a dependable engine for not too much moola. I wish you luck and hope you have fun with it.