Im****ting from US, advice required

I'm off to the US later this year. I'd like to buy a US classic car and 
bring it back to the UK.

I understand SVA is waived for pre 1973 cars?

Has anyone out there done it and if so how difficult is it?

I'd probably be aiming for an early 1970's Ford Mustang

All advice gratefully received

Thanks chaps and chapesses

Mart