I think I had some small combustion chamber 302 heads (D0OE I believe, without air injection ports) on my 1984 block when I put it into my '79 Capri. If memory serves correctly, I think I went bonkers trying to get the pushrod length correct (as the cam was non-standard base circle
). I ended up shimming and getting some locknuts so I could adjust the rockers to get the proper geometry. Yeah, not the most scientific way to do it, but I was 17 and just wanted to get my car on the road!!!