I suppose we can talk on as many threads as we want about cost of engine rebuilds or swaps etc etc, but the hard facts are don't matter what approach is taken, if doing it right it's going to cost big money... Whether a 2nd hand bottom end is bought like I mentioned or a rebuilt block like you have mentioned... There is still a lot of money to be spent on all the bits that you never really put much thought into....
If he has a new block sitting in front if him he still has, heads to sort out, head studs, head gaskets, rocker seaks and gaskets, cam seals, inlet gaskets, exh mani gaskets, plugs, oil, filter, timing gear, timing belt, new modine, new oil pump.
So at a guess still another 1200 quid to spend after he has block sorted.... The joys of it