Oh man.... I've been wanting to do a KX500 Kart engine for some time....
Jason Tanner who does all my builds for me has been doing several CR500 Kart motors but it seems in that game KX500's are far and few between.
In fact, his build won the local championship last year.
https://www.youtube.com/watch?v=wEC_voeVpwsCan you make the KX500 competitive?
Oh yes you can....
Most of what you said you would like to do is ok.
But there is some easier ways to do it.
Don't raise the transfers or ports... Lift the entire cylinder using a spacer and two base gaskets.
A good number to shoot for on the port timing is 191.
191 give a good all around power range...
Don't get me wrong, 194 will work but it will start making the engine a bit peaky.
You can get really close to 191 by lifting the cylinder approx .080".
That means you would need a .060" aluminum spacers available from Cometic, one .020" standard base gasket, and one modified .020" base gasket also available from Cometic.
But before I go further, is the engine pulled apart?
If not, watch this vid and get the info asked for.
https://www.youtube.com/watch?v=eTjceU2M7kw&t=110s