If the engine is the 318 that the first part of your build thread shows is still the one you're going to use, why not just use the stock Mopar flex plate? Converter wise, unless you're looking for some type of performance converter, why not use the 1968-1974 stock converter. All 318 and slant sixes used the same converter, and the factory offered two stalls, a low stall, and a higher (slightly) stall unit. The converter will have a 1.810" pilot and two small weights welded on the front(pilot) side. Just don't use any USED converters. Get a rebuilt one.
Keep it simple.