360 heads on a 318 of any benefit?

Allrighty guys, let's say I tackle my 318 heads to keep compression as high as possible what angle do I want new valves cut too or can I get them precut? If done correctly I"m assuming the seat needs no work to accomodate a cut valve...thinking out loud you'd have to add material to compensate and it would nullify the effect of the back cutting right as the point of the excersize is to increase the ease of flow...

Also how much benefit in the whole P%P process does back cutting give lets say in percentage in your opinion?

I'm still on the fence on the 360 heads...If I port them properly my biggest 'issue' will be a loss in compression due to the heads being taller and increasing combustion chamber size. How is that off-set by the larger valves which in turn increase air intake and thus compression?

Am I getting it?

Now as far as valves go I realize it's a question of taste/experience. What's the stock intake/exhaust size for a 318 and what for a 360?

340: what you're saying is keep the 318 heads port em' and get my exhaust out quicker/smoother with bigger valves...? For this I'll need to enlarge the valve seat. Porting and polishing I'm comfortable doing, valve seat idk...