I just thought I would follow up, as promised, with the results of my Rhoads lifter installation, and how closely matched your rochester carb was.
Before, I was getting roughly 10″ of vacuum at idle, and both you and I predicted that the Rhoads lifters should increase that by 3 or 4 inches…thus, you constructed the carb with this in mind.
Well, you nailed it with your choice of power piston spring. Before, the car was bogging and lurching with the other lifters (or 10″ of vacuum). Now it runs smooth and cruises at just above idle with no problems what-so-ever.
I will be referring others to you.