Propulsion Hegi Revell Fairplay V tug model
Indicated on these original plans are a 60mm diameter propellor, and the Marx Monoperm Super Special (what a name!) with reduction 3:1 in it. A choice which seems undersized to me compared to the (same era & comparable size) Bugsier Tug from Graupner which has a Decaperm.
For the moment I tend to go for this 12V low Rpm Xdrive 555. it has 25Nm of torque and doesn't need reduction. And combined to a Raboesch propshaft - which one can easily shorten - will help to get the driveline as far aft as possible in the boat, leaving more room for a bigger battery.(Or have the possibility to trim the boat with the battery and have the battery as deep as possible in the boat.)
I'll check these mentioned forums too, thank you for the advise.