Spooky tooth sells 'happy time'
kits & bicycles - in-frame, two-stroke.
For chain, you need (I believe) a #415 chain.
Here's a handy cross reference. Note that you can use #41 chain instead of 415 - it's the same pitch (and roller diameter,) but, it's a little bit wider than 415, and can handle misalignment a bit better.
Check out
Grainger industrial supply - they have several locations in the valley. Their stuff is very good quality.
There is a guy in Chandler/Sun Lakes who sells kits & parts - goes by LiveFastMotors. He's had
OK reviews here. You could get most of the external parts from him. (The quality may, or may not be what you would like. We have no way of telling.)
But, to tell the truth, if you've got a spooky tooth skyhawk motor, I would order any internal
replacement engine parts (pistons/rings/etc.) directly from them.