All the UK bikes seem to have ally tanks. One sneeze and they are dented.
I had a SP400 back in the day. It was pretty awful offroad, just didn't handle. The frame is identical to the 370 apart from the cdi mounts, excellent road frame though. 370s were modded by Vic Camp Racing for road race training courses. I put GN400 forks on it and modded the engine. It would do an indicated 90 with motocross bars and a belstaff jacket, and was uber reliable.