Isn't PB blaster a little messy. I just use carb cleaner when checking for leaks. It evaporates very quickly. Yes, tighten the three bolts last. Are you using a one-piece gasket with the metal toward the manifold?
My B always worked well with ported vacuum.
My 292 is fairly cold blooded and when I had the Roch B on there it needed the choke at stops for several miles until it was warm enough. Winter was worse. The Carter AVS 4bbl on there now gives a bigger throttle pump squirt and I don't need the choke as much when cold.

'67 GMC 3/4 292 4spd