Hi,
I see there has not been much response to your query, so I hope I can add some thoughtful observations on the model.
From the pictures I think the hull looks like a displacement design such as used for a fishing boat. As such a single propeller and rudder would have been more suitable. Twin props are more suited to a high speed hull and was probably a bit over ambitious for this design as it will never plane. If you want to complete the boat I would think about going back to a single prop and rudder.
The hull design is the kind more often used for a small live steam unit, possibly on display, as a gentleman's river launch for putting up the Thames. Not unlike the Billings African Queen.
It would be quite easy to make up a dummy steam unit with a small brushless motor hidden inside; perhaps with the battery pack in the boiler structure.
I can see a lot of careful work has gone in to the deck and your late uncle would no doubt have made a fine model.
Regards
David