Using different valves, bigger will generally always raise compression a lil. The main thing here is they won't make a torque monster 'relatively speaking' unless they flow what a 360 head flows.
You want velocity with flow, not just velocity.
A factory 340 made what, 340 ft lbs of torque?
Make 318/273 heads follow with what some 587/915 castings flow and it can make 40 lbs more tq.
