86 was first year for one piece RMS, 55-85 were the two piece old school RMS engines.
a one-piece RMS plate will not fit on a two-piece RMS crank flange and vice versa,
i have a few plates around here i think i have a 153 tooth 400sbc and 454 one also somewhere still but i did throw about 15 plates away recewntly so it might be gone but i have some in the attic still, maybe its up there by chance
good luck