disc brakes on 70 cutlass

[chromefeet_withbeat]

Hey everyone, first off, I read most of the thread in the vault about disc brakes. Mostly about cross-drilling and slotting, I won't touch that.

My question may annoy some of you, but here it is:
Can you retrofit old drum brakes to disc on wire wheels the same way you would on regular wheels? In other words, should I go with smaller rotors if I keep the wire wheels? I've read that the rule of thumb is to have about 2 inches or more on the wheel side as opposed to the rotor side. So does that mean I can fit 15" rotors beneath my 17" wires?

Also, which high end brand do you guys like best? Which offers the best "bang for the buck?" The two brands I see mentioned the most are Baer and Wilwood (and a couple other I can't recall), but I've never bought aftermarket brake kits before, or talked to people who have used either/or, and I'm sure some of you guys have.

Lastly, how much rotor do you think I need for a 4200 pound dinosaur that will still have drums in the rear for the time being? Where would you guys say is the point of diminishing returns, rotor-size wise? It will be mostly street driven but is also well equipped for quarter mile blasts. Having braking capacity up front has nothing to do with allowing a high stall converter to spin up to its rating without breaking loose the tires, right, thats all the rear brakes?

Thanks for reading all this