Outer Limits 4x4 Board

Just thinking aloud and would like suggestions/comments/opinions etc.

I have a couple of spare 4.4 V8's and am contemplating fitting one into a Series 3.
I have 3 land rover 4 speed manual boxes, but I also have a few 3 speed auto gearboxes and few 4 sp manual boxes (borg warner 35's I think) out of P76's, though I'm not sure these would suitable.

Anyway.....
Has anyone done this?
How easy/hard was it?
What do I need to look out for / be careful of?
What other things do I need to upgrade,strengthen etc?
What do I need to mate the engine to gearbox/tfr case? and which gearbox is preferable to use?

Thanks in advance for your suggestions, comments and flamings

they have a lot of torque, 2wd would break rover diffs and axles. Auto would be easiest on the driveline.

I've almost finished a 3.5 into IIa if its any help to you?

Which type of 4 speed?