Slight delay on this post but yesterday I set about drifting out the old valve guides and drifting in there replacements. I had bought the drifts from Dingocroft for this.
It took a significant amount of effort with a dead blow hammer to remove the exhaust guides, especially No 1. The inlet guides were significantly easier. The replacements went in reasonably easily until No 1 (I had worked left to right).


A wayward blow took the end off the guide so I have had to order a new one (actually two).
Whist on the head I also knocked out the core plugs and those from the block. The new ones seem deeper and I realised I took the cam end cover out too so will need another plug to well plug that.
I used a small cold chisel and mole grips to remove them and it worked perfectly well. Only one needed long nose pliers to recover it from the gallery behind.