End of my rope!

Ok guys. I hate to say it but I think I need professional help! I really hate the idea of being at the mercy of someone doing a diagnostic for a problem I wish I could figure out

So here's how it is. I hope someone recognizes the problem...

Problem: Loud tapping to a metallic shrieking, varying in pitch with engine speed. Is most prominant when applying moderate to heavy acceleration from either a standstill or low speeds. Problem is less pronounced at medium speeds with heavy acceleration but is still there. There is no problem at high speeds. Only is evident when vehicle is in gear.

What I've tried: Removal of the starter and use of washers as shims between the starter and cover plate solves the problem, however, this leads to an unacceptable amount of noise due to them improper mesh synchronisation between the flywheel/starter teeth.
I've removed and reinstalled the starter about 50 times over the past few months, trying slight adjustments - all doomed to failure.
I've ground away "the cage" of the the starter (and F* I was so hopeful ) but it didn't work.
I've tried a smaller shim to reduce the noise - didn't work.
I cut down the armature of the starter and ground down the grease cup area where the armature rests in the nose, effectively shortening the depth of the starter, thinking that maybe that this was striking a balancing plate on the torque convertor - nope
I ground down the base of where the starter bolts up thinking that maybe the balancing weights on the flywheel were hitting - uhuh...
I removed the inspection plate and bent the cover plate outwards thinking that maybe the mounting was pushing the coverplate in towards the flywheel when it was all tightened up.
When I turn the flywheel manually with the inspection plate off, it looks like everything has good clearance.

So were should I go from here. I've got some gas and there are lots of cliffs around. Maybe a brick on the gas pedal and a final blaze of glory!?? That would suck since this is the first car I ever owned and I've put alot of hours into it.

Some ideas borne of desparation: Junk from old starter bendix stuck in gears? Maybe that's why the noise is louder at certain speeds, in different gears? Wrong flywheel or torque convertor for vehicle (engine is a Maverick 302 - tranny is a Mustang C4)
Somebody upstairs hates me?

Thanks to those of you who took the time to read this, even if you can't help me. I know, this is a really long post. Ciao!

ok I'll give this stuff a try. The reason I haven't tried dropping the tran is that I seem to remember it being a big P.I.T.A. We had to hold the engine on a hoist out partway and bolt up the tran before sliding it into position because all the bolts weren't accessable when the engine was mounted. And since I'm the "new guy in town", I haven't worked up any "buddy points" yet - like what you need to find a guy with a hoist, etc.

I'll try the inspection of the flexplate with the rear jacked up (carefully) first.

Thank for all the input - I'll spare it the flaming death plummet, for now...(but that would make a cool video but preferably with a honda civic or something )