Good luck
The best I've heard a very good 170 inc fuel tank & all fittings fetching is £150.
Seagull 6's with the upgraded crankshaft must be 3 times that much, not much cheaper without it!
Why not buy a Kingfisher it's only the colour that's different, but check the cylinder condition, they're no longer available, same as the conrod, now you have to use century ones.
Make it idiot proof and someone will make a better idiot.