What year is the truck?? What heads are you looking at? Many aftermarket head man. have heads with different size combustion chambers to provide different comp. ratio's.
it is a 89 i was looking at the brodix ST5.0R or the trick flow R series. wich ever one makes the most hp i know the brodix heads have bolt-on 50 hp. i dont want my compression over 9-7-1. i will be running it on 91 octane anyway.