Hi ATS, the machine doesn't have give adjustment, it has a small built in give, but you can use a soft grommet or slightly open the needlle loop to get a bit more give,. You can also play with the stroke adjustment.
About the 4.5mm cam, I can make the stroke ajustment to give you a longer stroke, and that's it, you don't need a different cam, you just need to adjust it from 2.8mm to 4.5mm o
r maybe a bit more if needed, although I don't think you will need bigger than 4,5 mm, because with this machine, you can work with the tip of the needles without the need to press the needle down alot like some rotaries, (hope this make sense).
Any more questions feel free to ask!