k301 cylinder head differences
 

Got the head style with the spark plug over the exhaust valve and am wondering does it have any weird effects like overheating? I have the timing set to the standard starting point and then verified with Matts static method it was so close to not want to move it. It does not have the exhaust cover that covers the last part of the head either and ive notice while mowing with it say for 30 min that upon shut off it sounds like the gas is bubbling in the carb never heard that before and wondered if they are that sensitive the the heat sheilds? Or if it is the head style?

That's got nothing to do with the head design. You need to make sure the carb isn't set too lean and that all of the cooling fins are clear and there is no mouse nests under the flywheel shroud. You need to be running the engine at full throttle when under load.

Another thing that has nothing to do with any of the above...if the 1/4" thick gasket between the carb and engine is not there, the carb might be absorbing more heat from the engine as a result.