Me too. +1 on that - but I'm not familiar with Kibblewait guides others are talking about. My understnding is that a generally higher silicon content guide will allow a closer valve to guide clearance - I'm just not sure how valuable that is with a 50wt oil.whatever guides are used,paint a sealant into/onto the guide-rocker box juction of the guide bore. I have seen well built engines suck oil down the outside of the guide bores and smoke like crazy.
Kev