The guides are made out of a bronze alloy, and as the expansion rate of bronze is very close to that of aluminium there are many who advice against using heat for guide removal. There's simply no reason to. Aluminium gets softer with higher temperatures, so it may actually become more susceptible to damage. I always press them out cold.
Installing new guides is different, I like to heat the head to about a 100C (212F) with the guides in the deep freezer (-18C) and the guides will slide in quite easily. If there's any indication of scoring in the guide bore, I use some sealer under the collar of the guide.
However, for some years now my favorite machinist has fitted K-Line guide liners to lots of old bikes around here, and from collective experience accumulated over these years, they do seem to hold up well. Not disturbing the guide to head fit is a good thing, and we're able to set the valve to guide clearances to very exact tolerances.
With the short rocker arms and relatively high lifts the sideways thrust forces transferred to the valve stems are high. To mitigate that I suggest buying a set of "Elephant Foot" adjusters from David Madigan. The factory added a similar system to the last triples, but the "EF" is far superior as it has a much bigger surface area, larger than the valve tip, and will slide over it while imparting very little sideways force to it. I believe David may be out of EFs presently, but contact him for an update. For such a superior piece of kit, it amazes me that so few have caught on by now. I have thousands of miles on mine, the clearances stay in spec forever and the former valve gear noise has subsided to a sweet rustle that's just an aural pleasure.