DrEntropy said:
Another thing: The large rubber "gasket" between the bezel and the dash
I could be wrong, but it is my belief that the earlier TRs did not have those. I've owned or parted out a lot of TR3s over the years, and never found any traces of that gasket, not even a black mark on the vinyl. No mention in the parts catalog that I can find (not that that proves anything). And there doesn't seem to be any need for it.
I suspect it was introduced with either the painted metal dash, or the later fancy wooden dash. The TRF parts database lists it only for TR6 ...