I believe the drains are 2499 091 The parts book has them in section 23-59-25 Drain - Folding Top Well.
Looks like they used them in all 1964-65 Convertibles and all '66 Convertibles except the B bodies.
Didn't spot a listing for the grommets, but aren't they just regular body plugs with a hole in the middle?
I've never run across them anywhere. One of mine went missing for a while, and the shop that did the top didn't have a source. He suggested a boat supply place might , but I just made a temporary replacement out of hardware store parts.