Scooter stopped running

[Darn8]

I'll try to make this as short and specific as possible.
I have a JCL-MP-150R (150cc, 157QMJ engine with EGR). A day or two before it completely stopped running, it started making what I can only describe as a almost sucking sound near the cylinder head area. Took a few things off and apart but couldn't find anything loose, broken or otherwise damaged. I suspect it's a compression problem (the valves not completely sealing). There was quite a bit of carbon build up on the head of the piston and the surface around the valves. My question is:
Would my best option be to buy a rebuild kit and replace the whole top end (cylinder head & cams, cylinder, gaskets & piston w/rings)? It's a 2008 with roughly 4000 miles on it.
Any advice is good advice. I know my way around cars and simple repairs ubt I'm a little green when it comes to scooters as I've only had it for just under a year.
Thanks for the help!
N8