I recommend you have a good think about what Octane rating of the fuel you will run EVERY time. Once you decide that then you can decide on the compression ratio to run.
Skimming the head will reduce squish clearance which is generally a good thing as manufacturers play on the safe side. It will also raise the compression, also a good thing for the same reason as they don’t want the bikes to blow up when you run them on what passes for petrol in Elbonia. About 12-13:1 should be the max, but I don’t know how bad your pump gas is. 14:1 for proper race gas. Maybe more if you are keen, but I doubt it.
Then you have to measure the volume of your head & do a little math, but if you'd included your bike & year maybe some kind chap has the info to hand. (I mean like do you have a 1967 KDX 400 or what?) This will be close (for the same squish clearance, math will equalise the clearance, butt from yor spelink this may proove difficolt –kidding dude) but bikes do vary so play it safe.
Oops I see from your profile it is a 2000 200.
I could go on about Maximum squish velocity but assume it will be about right for the intended purpose.
You should also poke some solder through the spark plug hole & measure the squish accurately. Measure in several places as head are not always square. You should take it down to about 1mm to be safe for a 200 trail bike. This may or may-not take the compression unbearably high.