Hi, waking up an old thread here, but maybe some are still looking for info about this (I know I was). I have tried this now with a new 242 piston, and it worked great.
Used a Dremel with wolfram tip to make space in the piston for the slightly wider crankshaft in the 444. I had never used the Dremel to cut in aluminium before, and it was quite quick and easy to make enough room.
I dont have access to machining either, so I spent around 1h with sandpaper on the floor to shave off around 1,5mm from the top of the piston. I havent checked squish, but at least it stopped hitting the roof of the cylinder, and i did not consider hitting the sandpaper again.
I have another 444sg stock (older type with double ringed piston with skirt all the way around in the bottom), and when comparing - the one with 242 piston seems to have alot quicker accelleration, and seems stronger. Starts easy and runs well. i havent done anything with the ports other than cleaning and polishing intake and exhaust.