Originally Posted by Stillboardin
My goal for this engine is to keep it close to stock looking but some mild performance and reliability gains. I want to be able to get in the car after it sits for a week in the garage and turn the key and start it up and drive away. I want a nice throaty idle that sounds strong.
Also, if I go to the GT40 heads I may want to upgrade to shorty headers. Will they fit with PS, A/C and Power disc brakes?
Shorties are usually no problem. If you don't want to spend the serious coin required to change to GT40 heads, you can port-match the J code heads to the exhaust.
I can't overstate the difference this makes. I have done it to my 289HP, which had better exhaust ports than the J code, and the difference was immediately apparent even still in the driveway.
Closer to your application, I once saw a 68 Shelby GT350, which of course had the same heads and crappy manifolds as your J code, and had been restored to fantastic show condition, except it had the C9OZ-C cam, and 289HP manifolds port-matched to the heads. Result was, it ran FAR better than stock, yet looked completely stock unless you were savvy enough to spot the manifold substitution.