Best coil, box , resister combo ?

The best cheap, easy fix is a GM HEI module and e-core coil. Indeed, for $45 you can get that in a new distributor (ebay). With big boxes like MSD, you probably won't get much better spark and some might almost be too hot and better for race only. Once they designed high-energy ignition (GM's HEI, Ford's TFI), they were ~97% to perfect ignition. The addition of coil-per-plug "distributor-less" designs might have gained another 2% (mostly for lower emissions), but you can't do that without a crank & cam sensor, plus a computer.