I wonder what you like or don't like in terms of how it drives now? Is it healthy? Do you travel/cruise in it? Mostly around town? It sounds like a pretty well sorted engine combo to me. A set of open chamber Edelbrock heads (88 cc's from memory) would help it breathe and should be (basically) drop in replacement for the 906's and work with the domed piston (but check!).
Perhaps there are other areas that would benefit from attention. Suspension? Tires/wheels? Exhaust?
I like how the motor runs and power it has. Been the best since I got the car over 25 years ago. The front suspension needs a rebuild, seems like I just did it, 20 years ago. When I built the engine I had purchased a set of performer aluminum heads for it. But things happen and they got sold and I went with the 906s I had. I drive the car occasionally and when I do, there is usually a trip out the country.
my goal for the car is I would like it to be a 12 second car. Always have, although never been on a track in all these years. She saw lots of racing way back when, just of a different sort. Pulling a wheel off the ground was cool though back then, but really not in the realm of a need. I feel like there is some more hp and torque to pickup, but as others have posted, without track data, or dyno, still doing a lot of guessing.
