How to get 400 hp out of 1971 340 .30 over

I'll ask them. I have been running 660's for the last few years, installed annular boosters, and a lot of jet changes to get them somewhat tuned for this altitude. I wanted something better without going to fi. I hope these are the ticket.
Have you Spoken to Steve Taylor? Carb builder in Tx. Ran Bandemere successfully.