I'm assuming running 93 octane is set in stone. What Cab said I would CC/measure everything to see exactly where you are at for SCR but IMNHO it is way too high from what you posted. Cometic makes thicker gaskets. I would not go with a wilder cam to lower the DCR, keep the cam that suits your driveing style. For manifolds the best are early 340 HP ones & magnums, '92/early 93 ex manifolds which have ~2&5/16 outlets. Holler how it turns out. I would stay with the iron heads (for now).