I'm sure the Mini would pull more than 80 (when it's doing 5500rpm) given more road but by then I had to brake for paddock hill bend. I'm sure some cars were just going round paddock flat out, but I chickened out and slowed a bit for the corner each time.
I had Mk1 Cooper 7" disks on a Mini I built about 10 years ago and, yes, they were rubbish. Luckily this one's got Cooper S disks and calipers and they're pretty good. It has a 1275 MG Metro engine, 12G295 head, SW5 cam and the usual Stage 2 stuff on it.