In case it may help someone. Distance from flex plate to converter was .518. The plate is .100 thick. Flex plate re enforcement ring is .128. So .518 - .100= .418 (distance from mounting surface to converter). Thus .418 - .128= .29 (clearance). The OEM Bolts are .3 - .302 ish. Not all micrometer precise but I'd say close enough. Ring was a little surface rusty, new Orielly ordered plate, etc.
Short version: If you do not space the converter away from the flex plate, and use the OEM ring etc, you will need new(thinner) bolts as mentioned earlier in the thread. Now to find some local or order...more waiting I guess.
I did notice(rough guess) the drive "flats" look to be about 1/16" different than the OEM. Guess we shall see how it all goes when I stick the motor in and try to bolt it all up and check tolerances. All new territory for me on the transmission stuff.
445 FE and 4x4 Short C6