[Bill Pritchard]

Welcome to the site. To answer some of your questions....

1. Unlike the prior poster in this thread 'kenbrogan', your car's VIN indicates it was originally produced with an 8 cylinder engine, so that's a good start.

2. Rear axle and trans pictures you have posted have good assembly dates that line up with your car's scheduled production date (from the Trim Tag) of 07A (first week of July). The EJ code on the rear axle indicates it was originally equipped with a 4.88 positraction differential, and had metallic brakes....both very strong indications of a car ordered with drag racing in mind. I believe the transmission should have a partial VIN stamping also, but it could be up on the top of the transmission where it would be extremely difficult to see with the trans still in the car.

3. Unfortunately, if there's no build sheet in your car now, there's no way to get one.

4. Not at all unusual to have no factory tach, as anyone who was going to be doing serious racing would install their own aftermarket tach....the factory pieces were never known for being perfectly accurate, and often were located out of easy viewing.

Can't help with your missing/incorrect pieces but others here might have some ideas.