well, kinda a contradiction there!
8000rpm, no need if your wanting grunt.....youll just be wasting time sitting with the power falling off.
Megane head vs 7P head, indeed...........would be lovely to have both to test.
Why not (since your a tunning company and can afford it
) get the meg head and cut down teh middle of each port for a crossection, look how much material you have to work with, then work both heads and test them back to back at the lifts your going to run. See which flows more.
The 7P design is good in the bowl area, great for slowing gas speed as it turns and enters the chanber, you could tig weld up the throat and reshape it, see if you cant come up with a definitive shape.
Ports too big though, depends where your going though. The 1.6 4AGE engine which is one of my faves came in a small port and a big port TVIS version. The big port is used in formula atlantic making 245-250bhp @11,000 rpm............but the small port is the more streetable head.
Up tp you, would love to spend some time looking it over in detail though.