Good news

Good news, the resin holds the 3mm stainless nylon locknuts for the arneson drive mounting screws prefectly and I was also able to unscrew all 8 without too much problem ... pheuw I can take a deep breath cause I really was a little worried with this step.

Important!! DO absolutely put grease on all of the 3mm drive mounting screws and the back of the drive plates. It seems that the resin does find its way around.

Regarding the screws, M3 x 10mm seems to the the right length for the arneson drive mounting plates if you have reinforced the transoms of the sponsons.
M3 x 10 also works well for the drive shaft support plates.