Berkeley:
Ive currently got a P210 so much of what i am about to say relates to the differences between it and a 445 that a friend has. He has just converted that car from solar/electric that somebody in AZ did, to a B20. He tells me that he has some clearance problems with the steering column and the B20 motor mounts. He also said something about a different clearance between the radiator and the fan/front of engine. Just some things to be aware of when you go searching for a car. My ideal would be a 65-66 late 544 with the slotted wheels.

My thought would be to start with the latest and most sound (read rust-free)body tub you can find unless of course you just have to have that split windshield.

Good Luck!
Bob Tescione