Whats your price range? I am sure the eagle eyes on here can find some gooduns that would float your boat....
I'll start http://www.classiccar.co.uk/nissan%2Bdatsun/240z/lhd-datsun-240z---historic-rally_33734/?sort=price.desc&price_min=15000&price_max=30000&page=6&limit=18&back=
Yes you will probably loose money on the BMW, no matter if you sell now or in 6 months time, but I would also look for people with classics that would part ex or swap for your car