downright confused

I would do the opposite. I would either use your converter or "buy a nice" neutral balance, and then buy the proper aftermarket weighted flex plate from someone like BM This should still be an LA, not a Magnum, so make sure you get the correct one.

This is because if you ever decide to put a neutral balance engine back in, all you'll have to do is change to a stock flex, and it allows a lot more latitude on converters, say, if you were to run across a good one. Even if you find a weighted one, it's easy to knock the weights off