Hi Rhys, always nice to see an old model boat get some much needed attention. I have restored several boats over the years, some for others and some for me.
I like to do a sympathetic restoration keeping the character and appearamce as near original as possible. I did two boats for a lady some years ago, they had been made by her father during WW2 and very respectable models they were having regards to shortages and restrictions
Both were sailing models about 30 inches long. I came up with a few options and then asked her what her dad would have done today were he still here. That was the trigger and I installed radio all concealed in one, this was also modelled on a fishing boat, I suggested that many boats were later fitted with an auxilliary engine with prop out to one side, and that was agreed.
The other was a pleasure sailing boat, I did this after demonstrating that the first one came out as wanted. With this one I suggested that the sails be radio controlled with the sail winch in the hull but the endless line for sail control be clearly visible on deck, it is a bit of a quaint feature and came out well also making sheet control much easier.
Now if it is your boat then what you do is up to you. A previous post says go RC and I agree sailing is easier and RC is very small these days.
Then there is a really wrecked boat, I have just done a "resurrection" on a clockwork boat which was scratch built maybe 80 years ago. It did not look right but a bit of superstructure adjustment and throwing away some really heavy accessories has made it a much more acceptable boat.
If there are no other members in your family with any concern for what happens to the boat then keep everything looking as it was use modern technology and get her back in the water. Write some information down for the next generation and keep it with the boat. Also let the guys at the vintage model yacht group know what you are doing i.e. photograph the progress and let us know too.
Good luck and keep us informed.
Roy