Take a look at this disc brake conv. please

The ebay kit in post #1 is just the 73+ factory setup. All new parts, so high-dollar, but it is getting hard to find those cars in the junkyard. Might be the best choice since you are going to BBP in the rear.

For those staying with SBP wheels, the Scarebird kit is probably cheapest and easiest. Works w/ your existing 9" or 10" drum spindles. Wilwood also has kits for either drum spindle, so also easy work, but cost is higher. Many people need to rebuild their control arms & ball joints. In that case, changing spindles is no extra effort.