Would cast iron HIPO 289 manifolds fit the GT40P heads? I know of the different plug angle which Ford solved by using some wierd looking headers.
Would there be any interference with putting on plug wires?
I have a 3.08 axle ratio, so the 302-4 bbl engine doesn't rev up too fast (1800 at 60 mph, 3500 in passing gear), but it is real torquey with original stock heads and a 268 comp cam. Or are the rpms kept too low for the heads to make a difference?
Thanks.

 

At 1800rpm.. if that is your cruising speed this motor is outside it's "powerband" which is something like 3000-6000rpm with that cam and heads. There is nothing wrong with that you just have to accept downshifting as a fact of life and not be afraid to let her scream once in a while.

Can't help you with the manifolds, but from what I have seen you can make standard 302 headers fit these heads you just have to be prepared to message a few head tubes to clear the plug boots.

 

If you use anything other than a manifold/header made for the slanted plugs at least one of the plugs will just not be accessible. You will end up removing the manifold/header to change that spark plugs.

 

I haven't put GT40P or GT40 heads on yet.
I'm just wondering if it would be worth the effort considering the axle ratio keeps the engine revs pretty low.
Or would the low end torque increase?

 

Per a lot of thread on Mustang sites, the Hi-Po manifolds do work on the "P" heads.
Dave