If you plan to use the Getrag box, check the 5th gear ratio, as some Getrag boxes are direct top, and require a suitable long-legged diff ratio to loower cruisng revs to a tolerable level.

What sort of ratio should I be targeting and how do I tell if the box is a direct top?
Trif

Ford boxes are usually in the region of .87 for 5th gear, so a diff ratio of 3.6 ish is ok. If your box is direct top then you would be looking for a diff ratio of around 3.1 For your box google with all the details would be a good place to start, alternatively find a way of turning the input shaft and see what the output does.

3.14 Sierra Diffs Are very very rare!

TT

Indeed, which is why he needs to check the gearbox.

Thanks to everyone
 

Thankyou to everyone that has taken the trouble to give me help with this matter. I've got loads to go on now, and the first job will be to modify the chassis so that it will accomodate the engine and box. I'm going to follow the path of using the sierra donar, secure an age related plate and then convert to the Omega drive train................. I think!
Cheers Trif