The 266XP seems like an orphan when it comes to top end parts interchange.
Will a 268/272 Bailey's cylinder kit work. If mods are required are they extensive? (ie new carb, intake system, shroud???) Anyone do it?
If cylinder is excluded, will a Husky 66, 268, Jonsered 670 50mm piston kit work? I believe 266XP is also 50 mm.
TIA
This group of saws can be a nuisance, with a lot more variations than is usually the case with Husky. Everything will fit on the crankcase, but there are quite a few other changes that need to be made for some swaps. Most of it is in the intake systems as you mentioned. Intake block, boot, gaskets. The whole intake port face is a different configuration going from the 266 to the 268/272. The Jonsered saws, 625/630/670 did not get the upgrades that the 268 did, but there are again some differences from the Huskys.
Carbs are a bit of pain as well. Some had the separate pulse line and some didn't. On some models, the idle screw is on the carb and on others it is set in the case.
It can pretty much all be made to work, but you have to spend a lot of time sifting through the IPL's.
My opinion is this: If you already had the 268/272 jug, then it would make sense to get what you need to adapt it to the 266. But if you have to buy one, then I think it would be best to just get the 266XP jug and make it easy on yourself, because if you buy the 268/272 kit, your still going to have to buy all of that other stuff to make it work.