This frame is clean as a whistle, so oil/grease is not a problem.
The local radiator shop said they didn't think their tank would strip the paint.

Wow, Dodgy, I've never seen a frame dismantled like that, quite a job!!

Anyhow, I think I'll take to the sandblast place I've had do other large parts
and go from there.
I know they can't do anything about the the paint that migrated into the cracks around the perimiter, so welding on the seams will be problematic.

i'll resign myself to do the gusseting with the kit and leave it at that.

Thanks for all the ideas, Joe