Longer plugs for aftermarket heads?

Where did you buy the heads from?
Can you contact the manufacturer directly?
It is not uncommon to need different spark plugs with aftermarket heads. Either the thread depth is longer or the temp. range requirements are different, etc.

Some heads definately need the .750" versus the .700" plugs to get the tip into the chamber

Strike force heads????????? I think most aftermarket aluminum heads take a Autolite 3924. I would buy one (like $1.50), see if it threads into it, and check underneath to make sure it doesn't stick too far into the chamber (or not enough). Also see if the plug hole is tapered or flat, this will tell you if it needs a gasket type plug or tapered. If the hole is tapered try a Autolite 25 and see how that fits. Sounds like you might have to do your homework on this one. And after you get the car running you'll need to determine what heat range you need.