Which flex plate for MP 175k converter?

No. I still don't know what size bolts the 175k converter uses. I'm still hoping someone will chime in with that info. :) If not, I'll call Mancini and ask them.

But I did notice an error in the flex plate part number I posted. Instead of P4528751, the correct part number for that plate is P4529751. This is a SFI approved flex plate with 6 crank bolts and 7/16" TC bolts.