Are going to convert it to a roller motor? I did a bunch of mods a few years back with a roller 302 block.. it had stock crank and rods, 306 probe pistons that were .030 over with 8.5:1 before the blower. The p heads were worked and had 1.6 ford motorsport roller rockers. I went with a custom ground cam that was equivelent to the lift of an "X" cam. ( about .540 lift) my pushrods were not stock length and cannot remember the little specifics of it.. I built an 83 nonroller motor and had nothing but problems with that one.. it wasn't worth the money.. and to tell you the truth... either was the GT40P heads.. the explorer heads were okay back in their day.. they are a far cry from the GT40 heads. today I would have went with a set of RPS cast irons for the same price. Don't take this as gospel.. I had a lot of heart ache with this combo.. I wanted to build a race motor for the street.. I broke more things than I care to write about.. I paid more cash than I would admit.. and have made friends with the local flatbed driver, all for the sake of the Need for Speed... The motor finally crapped out when I lost a valve keeper down into the motor and you can figure out what happened there..
The motor ran 12.90 in the 1/4 and just didn't have any more pull on the top end due to the heads.. Now I have a 331 with reinforced everything!! 210 cc flowing heads with a custom .600 lift cam, 8 lb supercharger and big injectors.. It has almost 600 horses and I am afraid to run the damn thing because everything is just so expensive if it breaks.. does it make sense? I have about $8K in this motor and now the car sits in the garage most of the time... Now my new project is an 86 Buick Regal with a BBC and an 8-71 supercharger.. Once that is done right.. I am guessing it will also sit in the garage.. go figure????