Those 34s aren't gonna be horribly bad. As for alky I'd make sure you drill out the gas cap and take out the steel bearing in it. Also like they said bolting on a cub is a quick and easy way to bolt on 90hp and I think you'll be close with 34mm lectrons and a 421 cyl with good pipes. If you don't mind having 5 less HP and want to keep lots of torque get a "serval" cub cylinder. M/M, or McCoy's perf won't make you wait for ever to get em. They have em in stock usually, with domes, gaskets etc.
If your next post is a "what pipe" post. Shearers get my vote.