It is a 4wd, the gearbox will fit under the very high standard steering crack position, and essentially everything you said is rubbish because of those two points, BUT, thanks for the input mate, as I know you were just trying to help

Between the weight of the old engine and gearbox and transfer box and front shafts etc, it comes to almost the same weight as the new engine and box, there really is only about 50kg at most in it between the two setups, so overall weight will vary by about 4-5% or so, ie nothing to worry about, and like you say, it will be more centre weighted now with the gearbox back so far, so Im pretty confident it IS going to work ok now ive looked into it more, especially as having taken my own measurements from the donor car now, it looks like I can get the front of it a little further back then I thought when I first posted this based on measurements from the net.