Rhoads lifters bleed down a bit at low rpm with the lower oil-pressure, which decreases valve open duration,which increases the engine vacuum.
Do this;install a vacuum gauge on the intake,then slowly rev the engine up, very slowly. Stop as soon as you see about 13" of vacuum. All boosters have a check-valve fitting which "traps the vacuum". If the booster is working right, once it is charged at or above 13", it will provide enough power for at least one long slow braking glide from 60mph to zero. Whatever rpm you saw at 13" is the minimum rpm to keep the booster charged no matter what the car is doing.
Some boosters might require a lil less, some a lil more. With your cam, and a good tune, I bet that is gonna be about 1000 to 1200 rpm.
Try to imagine, on an autocross track, where on that track you will be at or below that rpm, and repeatedly stabbing the brakes, to drain the booster. My guess is it will never happen, therefore my guess is that a properly functioning booster will not have a problem. IMO it's a non issue with that 231/110 cam, she's a pussy. Well; more of a sweetheart; I really like mine.
I have a manual trans in my streeter. And one of the things I like to do is parade around the parking lot. With 3.55s my minimum speed is 4mph@550rpm. Yes that Hughes HE3037AL will idle down there, at 5* idle timing and a decent T-slot sync. With a little toe on the brake, and a little toe on the clutch to ease the bucking, I can get the tach down to 500, which is 3.6mph;a fast but not uncomfortably fast for most,walk. At 4/3.6 mph, I don't care about what the booster is doing. The 10" self-energizing rear drums have well enough power to stop the car, with a pair of 295/50-15 contact patches at 24psi. I don't even need front brakes at that speed.
But here's the deal; accelerating normally from a stop;1000rpm =7.3mph on my car, and minimum vacuum has been achieved; the booster is ready. And for my car, it will stay ready at all times that the rpm is over 1000rpm/7.3 mph.
Do this;
wind your car up to the highest speed you are likely to achieve in an event, in whatever gear you might run the event in, then apply the brakes to a stop, in as short a distance as you can. Do this thrice and average the results.
Now do it again,this time simultaneously put the trans in neutral and note any change in brake performance.
Do it again but this time shut the engine off as well. This is the ultimate test.
I did this with my 292/108. With a manual trans it was a non-issue. In fact, with 11.3Scr, the trans, while downshifting,does such a significant amount of braking, in a normal DD application, that the front pads last a really really really long time; to the point that I change rear shoes more often than pads.
With an automatic, if, IF, I would run into a problem, I would just install a dashpot on the throttle arm to slightly delay the last little bit of throttle closing, like was on the factory Carters. But I sure wouldn't ditch my booster. Not because I have chicken-legs either. I just prefer a booster in a DD. My left leg controls the clutch. My right foot controls the gas. Either foot could be on the brake, or both;depending on how things are going,lol. The booster allows a great deal of finessing of the brakes, and after 50 years of driving,both feet know the drill.
May the force be with you.....
