Mustang rebuilds are a waste of time and money these days, by the time your properly done, you can easily wave goodbye to 20 to 40k where you could buy in a fresh rebuild from the states for under 18k
A car left outside to the elements would most likely be a 6 cylinder notchback, in which case I really wouldn't bother, anything later than a 71 Mach 1 is not worth considering, bit like buying a mk 3 really
Get some pics up! If it says Boss anywhere on it, I'll double what you pay for it 
Thom
Its true that 'Stangs and all other actual 'Classic Muscle Cars' can be brought re-build from the US cheaper than doing a refurb over in the UK but at the same time, this car couldddd be okay and need little work... I'm yet to properly check it out and so can't verify the age and model for definate, but your probably right about the lump in it, could be a 289ci but I won't know until I check

If it is boss I think I'm gunna stay with it untill the owner sells it so no one else can take it!

hahaa I don't think it is however!
Pictures will be put up (Regardless of if I manage to buy it or not)

sometime in 2 weeks when I'm home