just get a a whole granada 24v.

Drop the full lot on its crossmember it will fit a Sierra - it was no problem for me.

You may want to change your rack, hubs, shocks, ARB, TCA's etc but I went for the 5 stud goodness and fitted everything except the shock and springs - I used Escort Cosworth shocks, same at the rear - just swapped the diff mount for a Sierra one, all I need now is a gearbox to get rid of the Auto box and I'm away....

Never heard of clocks from an XR4x4 working with a BOA? Is that a well known thing? It's just that I have an XR4x4 that a bloke converted to 24v and it has the Granada rev counter set in the Sierra clocks. Can't see him going to that trouble if the original was any good?

Anyway, horses for courses.

Theres a few ways of looking at it but I stumbled over a cheap Granada 24v so everything was there pretty much except what I mention above..