Hello Ian, thanks for raising Greyhounds on the Forum !
Yes there were only 84 cars made, mostly with Bristol engines, and only two with Ford 2.6, one as a prototype and one re-engined I think by the factory. I have not seen either of these and don't know which gearbox but would guess that the engines are standard. They live not far from me so I'll have another go at seeing them. Greyhounds were for many years not much sought after and not very valuable - the Bristol engine and gearbox was worth more than the car and consequently quite a few Greyhounds lost their engines to Aces, Acecas or Cooper Bristols. Sadly this is still happening. So there are quite a few Greyhounds running around with non-standard engines - Triumph, Rover, Ford V8 etc. Greyhounds are covered reasonably well in the AC books and Rinsey Mills did some nice research for his new very fine book. The one Greyhound in New Zealand has now moved to Australia.
If there is anything you particularly want I could mail to you directly
A Good New Year to you all
John