[Nas67stanger]

Lookin to get into some new heads relatively cheaply. I have a friend that has a set of heads off of a 1991 fox body 5.0. Will these heads work on a '67 289? Will they bolt up? Getting them for $50.

[EagleAutosports]

Yes, they'll work. Shouldn't have a problem.

[Nas67stanger]

Will they give me an edge as far as power goes? I am running a 289 performer intake with a Holley 600 carb. I put a little bigger than stock duration cam in for a better power band. However, I am still running stock California Emmissions Heads. Will I see a power boost?

[shagadoodle]

i think you may see a decrease if they are stock heads from a 91 fox body. very restrictive heads. i think its one reason why fox bodied mustangs didn't have all the power classics did.

[Nas67stanger]

i also have access to a set of mix date matched HI-po heads. Would these create the extra horse I am looking for?

[shagadoodle]

yeah i think the hi-po heads were aluminum and obviosly hi-po so they should get what you want. im still learning so don't take me 100% on what i said.

[Scavenger67]

I am also contemplating this swap with 5.0 heads on a classic motor. What i want to know about is the push rod length and how the rocker arms are going to work. Next the Hi po heads are cast iron but they are still better than the E7 TE heads but they will also probably cost you alot more. here is link to a site with flow data on both heads. StangPro.com - Ford's GT-40P Cylinder Head.
As far as a power increase you probably won't be able to tell the difference with the e7 heads for the trouble it would be to change them.