Thanks all for the advice

I will give it a bit of a tidy up...with a brass wire brush. I foolishly left the pistons exposed overnight without oil on them and they picked up a little corrosion. So I'll brush that off as well.

I wont aim for a mirror shiny finish on the top of the block - just remove all the old gasket material and brush it up fairly smooth.

When the decked head comes back I'll reassemble with a new head gasket and see how it goes.

Thanks again for the re-assurance...hope I didn't hijack this thread!