Ram Air manifolds were powdered coating including the flanges
 

Should I remove the powder coating off the flanges before putting them on the the heads are with the gaskets be good enough they seem pretty flush, but I don’t want to leak either

I'd run a file across it all just to may flat, even if coating remains. The powdercoating can have a slight texture and waviness that doesn't seal in all situations.

Use the remflex gaskets Gary and you will be fine.

X2. I started using them more than 20 years ago.