https://www.mopedarmy.com/forums/read.php?7,4275878
if you can filter out all the drama and blathering, there is some good info in here.
tl;dr
Dont call it 65 or 70 cc, that isn't the actual displacement on any of them and it confuses the hell out of me, just to bitch a sec...
44 is a great easy slap on kit, great finish out of the box, easy to tune, runs great with a 14 or 15 bing and proma GP or Proma Circuit... or probably any other basic pipe. good torque, like a stock cylinder but just a lil' more.
Danny mentioned something about liking the 45 mm airsal, he'll probably post on here. My memories are fuzzy but i recall it taking a little more cleanup, bigger transfers, etc. I think its a 1 ring piston out of the box. Probably better to build it with something like a VM18 (phbg if you have to...) and a tecno estoril, gonna go faster but you'll have to put more work into it.
for za's its nice to not have to put a crank in them and keep them mild. Once you start pushing them they tend to break stuff if you don't do a full blown rebuild.