Hello all. I need help identifying a bicycle, again.

Here is what I know:

Serial #: 7E00449
Panasonic Drop-outs (Front & Rear)
Crankset: Shimano 105
Shifters: 7-speed Shimano 105
Brakes: Shimano 105
Front Derailleur: Shimano ?
Rear Derailleur: Shimano 600
Rims: Mavic
Hubs: Shimano RX100
Headset: Generic
Seatpost: 26.8mm
BB-TT (C-C): 55cm
TT (C-C): 55cm
Weight: ~23-24 lbs on my crappy fish scale

The serial # indicates that it is a 1987 model, but beyond that I'm not sure. The guy that I bought it from was told that it is a DX-4000, which would make it Tange Champion #2. I have heard that the Tange tubing sets use the same size seatpost. Is that true? It has been powder coated, I think, so there is no original paint or decals. Is there any way to tell the exact model?

If I were to guess, I would say it's a DX-4000

This is the place to go!
https://panasonicbikemuseum.info/

Been there, numerous times, but without the original paint, decals, and possibly components, is there any way to tell for certain what frame it is?

The only problem I see is that that is not the correct fork for 1987 DX 4000

The fork does look more like the DX-5000 fork in the catalog, but google image searches showed DX-4000s with a similar fork. The components do not match up with anything in the catalogs, 1987 or 1988.

Chukk, do you have any photos of the bottom bracket? The non-drive side crank arm is really close to the BB. I think that lower end models had more of gap.