Hi Eric,
I suppose when you say you are boiling out the air bubbles your are really using a vacuum pump to evacuate the air? (You know that not everybody works in the air conditioning field and has access to a vacuum pump!).
I hate to admit how long I have had silicon brake fluid in my 66 Alpine. Its got to be over 20 years and still holding. I remember it was a good name brand of silicon fluid. I think it was a GE product? In any case fellow motorists, I am going thru the car now and will be rebuilding and changing the fluid. However it is still working. Duel cylinders does seem like a good idea.
I think and someone correct me if I am wrong that the boosted original cylinder was .75 (3/4") bore and the non boosted series I and II used a cylinder with a .625 (5/8") bore. I have driven my Alpine thousands of miles using the 5/8" bore cylinder and no booster and stainless covered flex hoses and have been really happy with the braking.
Dave Reina
Here is another thread on the subject, with testimony from Tiger Tom:
https://www.teae.org/forum/viewtopic.php?f=1&t=983
I’ve taken additional steps to insure all the air is out of mine, and my Alpine has a solid pedal with DOT5.
Here’s a demonstration of all the air being boiled out of a sample of silicone brake fluid.