I keep reading on here about all the work these heads need for them to perform. My question is do i have to do anything to them? i'm not going to race it. I was hoping to just bolt them on and go. I'm wanting to build and get the most out of this 521 street/strip motor i'm building. It wont be a daily driver but i will drive it on the street and may occasionally show up at the mud runs and run it a time or two. One more question; I have a C8 block ready to build and a D9 block. which block should i go with? should i go with the D9 because of the longer cylinder walls for the stroker or will the 68 block be fine. I have the ford racing 514/521 stroker kit. I believe if memory serves me correct the pistons are a 18cc dish which with these heads should yeild about 10.5:1 CR. I have not bought a cam yet as up to this point i wasnt really sure how i was going to build this motor. thanks.