@Stan Galat posted:A bit of housekeeping: I got my first service call at 2:30 AM yesterday, and we've been buried for 3 weeks at work. I made the mistake of commenting on this thread before I read the entire thing. I deleted them both this afternoon because they weren't relevant to the discussion. I'd like to say I'm sorry, especially to @DannyP who took the time to reply to one of the comments.
To the business at hand: All of the advice has been solid, especially when Danny said:
... with an addendum (which follows).
There have been a lot of advocates for rear drums over the years, with comments generally along the lines of "drums on the back are good enough". I understand the sentiment, but I don't agree. More braking power is always better. Always.
Something is important to note, however. Almost all of the commonly used disc brake packages are from EMPI or CB Performance, and these use the same front and rear calipers. It's a bad setup - the rear caliper bore is too big to be matched to the front. The net effect of this is that under hard braking, the rears will lock up before the fronts, which is less than ideal.
Henry at IM knew this for years, and his 4-lug setup was fully custom and used a hub from some economy car, a replaceable disc from something else, a rear caliper from a VW Golf, and a custom caliper bracket. The balance is mathematically perfect.
We had discussed the rear brake bias of my CB kit many years ago, and he had let me in on the "why" he did what he did, which was a powerful reason he built so many 4-lug cars - the brakes, as delivered worked beautifully.
Henry recently purchased a car he had built back in 2003 from the widow of a client who lived about an hour and a half up the road. It had the brakes I'm talking about. Henry and his daughter flew into Chicago, took a bus down to get the car, then drove to my house where we put it on the lift for some service work. He and June stayed the night with us before they left the next day to drive it back to Vancouver.
As an aside, I'd like to extend this invitation to pretty much anybody on this forum who needs a place to work on their car (and a home-cooked meal and nice bed) on your way from here to there. Flyover Country has a lot to recommend it - spend a few hours here, and you'll wonder what all the fuss on the coasts is all about.
Anyhow, while the car was on the lift, I looked at his setup and started thinking about the problem of mismatched brake components, and how little thought any of us really give to the most important component set on the car. We just assume that somebody smart put it all together.
As is often the case, this is just not true. Certain parts were used because they were available and cheap. AirKelwd, CoolStop, etc. are likely better engineered, but I've got no way of knowing. I'd trust that CSP brake systems are well engineered, because they are TÜV certified. Beyond that? I can tell you that the EMPI/CBP stuff is "homemade" in the worst sense of the word. By way of full disclosure - I run a CB kit, and it's "fine" for the way most people use their car. However, I don't like settling on "fine" - I aspire to do things "right".
I suppose one could use a proportioning valve in the rear brake line, but that seems like a Rube Goldberg "Radiator Springs" way to do things. I don't aspire to be Tow Mater.
The reason for this long/boring piece is to say that whereas most aftermarket disc kits are biased to the rear, that would never be the case with a front disc/rear drum setup which may be why a lot of guys want to run them. That's the nice thing I can think to say about them. I personally don't think the answer to the riddle lies in reducing the size of the rear brake, so much as increasing the size of the front caliper. I'd want to talk to somebody smarter than me, but I think the typical Varga rear caliper (with E-brake), matched to a 2 or 4 piston Wilwood front caliper would be a much better way to go. I'd still want to know what MC would be best to use. I'm not trusting the brain trust at EMPI to have done any actual math.
To conclude, I'm not interested in reducing braking power to get better balance. But better balance with more stopping power would be great.
That car came with a hard top ... a very nice one to say the least.
BTW, on my build the master builder's secret sauce 
he calculated the pad surface area and the number of pistons in the calipers for both the front and the rear disc brakes to comply with a known car AFAIK.