S11 engine/box swap

I have a 1962 swb S11 rebuilt on a galv S111 chassis. The gearbox has had it, and the engine compression is very low.
I've been offered a sound normally aspirated 2.5 deisel complete with box from an early defender. I can see that the tunnel will have to be modified or replaced to acommodate the different gearsticks, but to my eye everything else looks as if it would fit straight in (apart from moving the battery).
Is this right, or am I just being a naive fool?

I don't think the Defender gearbox is compatible with the series transfer case, the Defender having constant 4wd, I don't think the rest of the Defender running gear would be compatible either. The easiest way may be to get a reconditioned series gearbox and get an adapter plate to mate the 2.5 diesel to the series gearbox.
Though there are some clever people out there who may offer a more acceptable solution.

Kind regards...Ron