Ah, man, that doesn't sound good. Knew the arches would need another going-over at some point but the rest is a bit of a shock. Maybe if you have the track bug the looks are less important than they were? Do what needs done to get through MOT then weld out the bad bits, keep going with the tubby and respray in time for next JAE? Suspension and brakes would need replacement/refurb if you intend serious track abuse anyway.