From what I've read, for a B series engine, one should only need to tourque once at installation, then again after a short run-in period, often 500 miles is mentioned. However, opinions on this vary. The payen gaskets do seem to compress a little after first installation. When I rebuilt my MGB's engine, I checked the head and found that re-tourquing did snug the nuts down a little further after some hours were put on the engine. I won't touch it again though.
Ed
I want my MGB