That being said, of your crank is good and reusable. There are other ways to go about more power. You could get a Sachs Athena and run it mildly detuned and not burn up you clutch...that with a 15carb and intake with your stock crank might get you to 40 without a chamber at all....it's a 70cc kit that is capable of burning clutches like tissue paper, but mildly built with the stock crank and no pipe might be great...yould only need a cheap bearing and seals kit to instead of the whole shebang....
https://www.treatland.tv/sachs-athena-70cc-kit-p/sachs-athena-70cc-kit-074000.htm
Remember I could be talking out my ass here....but i would prefer a d setup with a carb and chamber before the kit tho.
Think your gonna need a Sachs thread flywheel puller, circlip pliers, and some other stuff for disassembly/reassembly