The early TR7 takes less turns of the wheel to go from lock to lock than do the later cars. I think it is something like 2.8 compared to 3.5. That is good on a race track or autocross circuit, but requires more effort on a road car. I personally like the early quicker racks, but I can understand why Triumph went to the easier to turn slower racks. I assume many of the early TR7 owners complained about the steering effort required to turn the car at slow speeds. The quick cheap answer was to go to the slower racks. On the 8, they installed the PS rack, which is similar to the Jag units of the day. They even use the same rebuild kits I have been told.
As far as the poly bushings go, they are all the same. The U.S. supplier is British Parts Northwest. So whether you buy them from BPN, Woody, or Ted, you are getting the same things. Buy from the vendor who offers you the most tech help. By the way, the same basic routine goes for headers. My first call is always to Woody, but my reasons for that is a story to be told in person. Woody's Willwood brake kit is amazing. He is the king of making TR8s go faster and stop quicker.