Sorry to be so indefinite, Bill. I'm certainly not willing to say you <span style="font-weight: bold">must</span> shim the calipers, as I don't know how badly off-center yours are. On my own car, I removed the shims with no apparent ill effect ... of course I was also changing almost everything that would affect the alignment of caliper to rotor (calipers, rotors, hubs, vertical link, caliper bracket).
I was just trying to present some reasons why the factory may have felt it was important to shim the calipers. Oddly enough, this does appear to be something of an afterthought, as the shims don't seem to be listed in my TR3 factory Spare Parts Catalogue; but they are listed in the TR4 version.
Don't have time to check just now, but ISTR the VTR website has a fairly good list of the minor details that changed with the TR3B. There were actually two different series of 3B, if I recall correctly the later series even got the TR4 4-synchro gearbox. But since all of the distinguishing features can easily be installed on the earlier cars, I'd say go with whatever commission number plate you wind up with. If it's a TS- number, call it a 3A. If it's TCF- or TSF-, call it a 3B.