300k on the clock.
RWC - not sure, haven't really looked. It definitely needs tyres and the exhaust fixed. Shouldn't need too much more than that, unless you take it to a really fussy RWC place.
Economy - no idea. I can't drive it anywhere so I don't know . RB30s in good shape tend to get decent economy though (for a 3L 6 banger, it's not going to be as good as a barina).
I can include some lowered suspension for you to chuck in it if you like.