CD90Z - interesting cam sprocket setup

Following the cylinder & head stripdown I noticed something a bit odd on the method used to bolt cam to sprocket. On investigation in the manual/parts list I discovered bolts were screwed in from the wrong side and had nuts on - ugh. This meant the bolts had slightly caught the head. New sprocket and bolts purchased. I ground in the valves, cleaned up the head cylinder to cylinder surface with fine emery cloth and a sheet of glass. I found a thick felt tip worked well for checking the head was flat. I reassembled the top end with a new cam roller bolt, gaskets and oil seal for the exhaust valve (I did find the old one - totally hardened).