Hi,
I got an MC16 with siezed engine for £350, I got an MC18 engine for £150, then sold the bottom end for £100. A few gaskets / clips rings etc later and it was running. I think it goes a bit faster with 18 barrels / carbs, but as it didn't go at all before that's not difficult!
It even passed an MOT after a bit of work!
Mat.