double hump head mods

I have a pair of the following heads and would like to know what would be some good mods I should make to them. Nothing too wild

1968-69 3917293 307,327 1.72 1.5 75CC

The only other mods I intend on making are:
Holly Street Avenger (570 CFM)
Edelbrock Performer Manifold
Keeping the powerglide but swaping out rear gear to 3:55
headers???

bowl work a nice 3 angle or 4 valve job. back cut the valves and some stainless steel valves