As a gesture of thanks to this forum you should use one of their sponsors, however my favorite
www.everythingcarts.com do not offer the full rebuild kit. They are all made by the same people in India so don't worry about price v. quality.
If you get the full kit you will end up with a new engine and your price target should be < $400. If you elect to just do the top end look for <$200
Before you make a decision grab hold of the drive clutch and ty to lift the engine. If you see any movement of the crankshaft relative to the block then your bearings are shot and you really need to address that. If you decide on just the top end kit, which is a cylinder, piston and gaskets then I urge you to also purchase new crankshaft seals. These are, second to the piston, one of the most important parts instrumental to the smooth running of your engine.
Anyhoo, as I like to say, it is your cart, your money and your call. Let us know where you want to go.
Dave