I got to agree with the general. I've seen my share of rusted out freeze plugs ,and have a tool to install new plugs while engine is still in the car.
Seems They should have replaced the freeze plug and been done,sometimes greed bites them in there ass.
If I'm in your shoes I am going to take anyone of those blocks to a machine shop, have them clean it up ,bore it ,line hone ,new cam bearings,ect. Then new forged pistons and rings gapped for boost. Then you can use whatever heads and cam you have and have some fun.
You replaced the distributor? Most new ones are absolute :poo:. My car ran like crap and stalled/shut off,I replaced three distributors from O'Reilly s.
Just maybe that's your problemo?