performance options w/o cutting case

[Marc]

They are "A" pistons, intended for use on a 69mm stroke. I think they're a great idea and I recommend them (for a 1679).
There's no guarantee that zero case clearancing will be needed with a 74, one always needs to check, so IMO that's an artificial "barrier". Most used cases need other machinework such as line-boring or case-saver installation anyway, so it's no big deal to have them opened up for a larger bore at the same time. Silly to spend good money increasing displacement the hard way (and cheap cast cranks are a bad idea) when comparable displacement is so easily achieved with bore increase only, but the question was asked.