before i spend all this money to buy the edelbrock performer rpm heads, do i want angled or straight plug heads? Its on a 72 chevelle with a 350. Will my header selection also be affected?

My personal opinion, no way the tiny benefit of angle plug heads is worth the aggravation. If you run angle plug heads, you will probably have to hammer a couple of the primary tubes for spark plug clearance, and will probably still melt plug wires. That's how it went with my 69 anyway.

all out racing might make a difference but im not a expert as for as headers, hooker super comps will work with either head as for some others. but many headers will have to be altered in some way

Which design makes changing plugs easier with headers?

Straight plugs are easier to replace. I don't think there is any benefit of angle plug heads with flat top pistons.