The biggestroblem with using different heads, is that, you'll loose compression. You're 289 heads have about 53-55 cc chambers. A lot of 302 and 351 heads are in the 60+ cc range and will loose about 1/2 or more point of compression. I'm not saying this is the best thing to do, but I think if it was my car, I'd put the larger 351 valves in the 289 heads, using the Manely undercut street valves and a little pocket porting and leave it at that. This shouldn't really cost too much more than a good rebuild.
Tom
You can do anything you want to......ONCE!
aka "my 66 coupe"
Tom
You can do anything you want to......ONCE!
aka "my 66 coupe"