One of the major grounds is the one attaching to one of the bolts that hold the tranny on to the block (top of the bellhousing closer to the front of the car). If that is disconnected, frayed, or damaged you won't even be able to get her to turn over.

One other thing I would try to do is put jumper wires on the starter. If it cranks you know the starter is good, and the search continues. If not, then you need a new one.

Are we sure the timing belts, and auxiliary belts are on properly (not too taught)? If the belts are too tight it could cause too much friction for the starter to function properly. Also along these lines check the clearance of the power steering pump pulley. This bastard can be a pain in the ass to line up properly, if not it will rub against the water pump pulley and also cause quite a bit of friction.

I would check up on these and then post back up with results. Good Luck.