Damn, just caught up on this, I'm way behind here in the shop.... I see I could spend lots of time responding to this thread. Let me try to answer this as efficiently as possible. The 66 series BB turbos are my favorite, we know that already, the 6765 is pretty much a similar turbo with some components most likely shared.

I like and sell the PTE turbos as well, they are excellent turbos and Harry has taken care of us and the Buick community for a long time. I just prefer the Turbonetics version for the many reasons I have listed here and in other threads.
Do we need a 3400 stall, non lock convertor for it to work .... no. Would it be nice.... yes. Usually 3200-3400 stall lock up or non-lock up work fine. I just know that non lock up is my favorite, I like and sell the real Art Carr convertors as well as PTC and Pro-torque, the convertor choice depends on what my customers needs and requirements are. And yes.. you will make more power at 18lbs.... but I highly recommend we get you into Alky injection... you sound like you want to make power on the street, it only makes sense to do it with Alky.. and do it safely. Also, a turbos spoolup and power really is dependant on the surrounding combination one has.. a 66 with a stock convertor is not gonna work very well... a \good inter cooler also affect power and spool up, we also found using a 4" inlet pipe instead of a 3" pipe made a big differance in spool up, I was surprised as Brian L made the change and gave us that info...