Thanks for the responses. Always an interesting bunch of people on this site!
Transmission is an SM420, old cast iron bellhousing that fits SBC pattern and 1958 bellhousing crossmember support, stronger than stock 292 (when it gets finished). Wanting to build a low RPM torque engine.
I did measure the bore alignment (crank CL to register bore) using the magnetic base attached to the crank flange. 0.015" total misaligment. Measured a second time, 0.015". Took the measurement again last night after taking bellhousing off, making sure surfaces were clean, put bellhousing back on, magnetic base back on, measured 0.014" off in the same direction as before.
Checked the angularity of the transmission mounting surface to crank CL using the same magnetic base attached to crank flange, but now with the dial gauge sticking way out as far as possible on the transmission mounting surface. Maybe 0.001 - 0.002" of out of squareness, but this is close to the noise of the measurement. I don't think I'll need any shims to correct this.
I read some other forums, and there's a lot of opinions on what should be done.
I'll get my machine shop to install the offset pins. Better safe than sorry.
