Do NOT force it to turn unless you want to rebuild the engine. Read this before you do anything:
http://www.rx7club.com/showthread.ph...hreadid=281207
Have you considered taking the belts off and trying to turn just the crankshaft? Because usually cars only carbon lock from sitting for long periods. Maybe one of the other componants is locked up such as the air pump, alternator, a/c, water pump, etc.