Crank identification?

[Snakey]

Hi, I just bought a job lot of RV8 bits (just to get the girdle kit!) and the pile includes a V8 crank that's definitely not Rover - but I need to ID it before I can sell it.
Journals are 50mm b/ends, 58 mains, stroke about 80mm (all 'ish' - measured with our kids school rule!). Looks a bit roverish, 'cept nose is shorter with two small keyways and rear main is longer (with a separate seal bearing and HUGE flywheel flange).
Rear web is embossed 'GMT 8', front web '6764'.
Any ideas, anyone?

Snakey