Jim, Build one mate there are plenty of mk 2 shells that have been converted cage turets etc,You can then see it for what it really is..
Then as you know engines good spec pop up (cossie) for a good price

IMO it would be cheaper than buying one for 12k

Rollin shell painted etc £4000 that will be mint
engine (cossie) £1200 box £300 Loom £380 (new)

Thats nearly 6k and u know what u got 6k for wheels seats etc

Seen a few shells in back of retro ford for this kiind of dosh