The "BR" is Bender Racing and the "T" is for trail porting. Only my opinion, but your mentioned mods should put you in the 170hp range. Clutch it right and it will perform nicely.
I'm not sure what Bender may have offered in kits. Porting, pipes and CDI would be your best power improvers. Bender offered quite a few products for the vmax4 back in the day. These cylinders were likely just ported for someone.
What were the hp claims on the 880 setup? I always wondered how it compared to the 800 trail kit. I had a 95st with the Bender trail kit similar to yours, but ran it with PSI quads and it was insane how well it worked.