Hello,
A good source for the capped Kort propeller would be Cornwall model boats. But if you look at any of the above pictures, they seem to use what looks like an older version of Kort props where the blade corners are rounded and tops are flat.
I have the same boat with the old plank on frame hull in the works as well, I opted to make the nozzle from drain pipe which I'm still debating with myself about and purchased the regular four bladed Raboesch 70mm propeller from the same source since I'm a little concerned with it hitting the inner walls if it was fully capped like thier current offering, also it was a lot more reasonable in price
Thanks John (Oldiron) for the article it is exactly what I was looking for, I'll PM you if I'm ever going around Lindsay so I can see some of your awsome work in the flesh.
Hany