explorer 8.8 in an a-body: experience needed

Well... I am putting an 8.8 in my '65. It's $300 for a 3.73, limited slip, and rear disc brakes. I plan to buy a 2nd short axle and shortent he housing myself. I've seen 8.8s take 5-600hp with superchargers in heavy cars. I'm satisfied it's strong enough - and it looks a lot like the 7 1/4...lol. I figure with the new driveshaft and axle and misc parts I should have about $700 into it. Still less than a core 8 3/4 and all the stuff to outfit it similarly but without disc brakes.
On the disc conversion - I only have limited experience with that. but -when I ordered up the set of Baers for a customer's car, along with the hydroboost, the package came with 13" fronts, 12" rears, giant calipers, and an adjustable proportioning valve that the instrcutions had me place in the rear line. The car did have front discs originally but rear was drum and this was a competition brake package. I agree that most disc brake setups have a residual valve. However I do NOT believe it's used on the rear wheels - it's in the disc brake proportioning valve and acts on the two front wheel ports. This is why you have to get a disc brake proportioning valve when you change to front disc. I can say for certain there wasn't any recommended for the rear by Baer.