Servals are good for playing around.they like a drag pipe, & probably bigger carbs.
Ported 4mm stockers still run great with stock carbs, up to Atleast 80hp. If I remember right, servals can make 80-90hp on premium fuel if fuel is a concern.
If u plan on being really aggressive rider, jumping, etc you made the right choice. I duned a set of 22X10X8 8 paddle superlights & a 9 paddle set up I didn't really jump with those, but they were both a amzing. Both held up really good
Doubt u need to replace rings, just clean out the carbs & jets to get rid of the varnish & oil. Clean the fuel tank out & maybe that little filter inside the tank. Put fresh fuel in with good premix at 40:1 & new plugs. Should be fine to rip on it after a good warm up. Also change tranny oil as well.