On my Model H Rochesters (3 of them) I had to increase the accelerator pump openings to cure my off idle bog. I just drilled a second hole in each carb, starting out with a .015" drill. I had to step it up a few more times till I cured it, somewhere around .022". The extra hole points down right in to the venturi.
Since the engine is so low compression, bump the timing up till runs better, even with low grade 87 octane, it should never ping. Mine runs better with more timing.
Joe
