I think you might be asking for trouble putting juice on a motor with cast (hypereutectic) pistons, especially one with pretty weak stock heads & cam, too. I'm not trying to discourage you at all, I just don't want you to blow an engine. There's a LOT more power to be had just getting a roller cam conversion, heads, intake, and some headers. In your case, an Edelbrock carburetor too. At least that's what I did for my '79 Capri.
------------------
Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch