Thanks for the advice guys :) I fancy the skimmed head route as the valves as far as I remember are slightly larger, and the head also allows the use of inch and half SUs, not just inch and a quarter. (Open to being wrong on that one!) As I don't have a 1300 head to hand, I need to find out how much to skim off, I'm sure I remember a site that either had exact measurements or a quick rule formula. I would guess around 2mm to 3mm, but do you have any robust ideas? Thanks again Dan