I didn't see the k&n mod
The yfz450 conversion can be cheap and really
Good
Your domes are 20 what is your compression?
If your close to 150 than your good there.
You might want to mod the tranny so you can shift with out the clutch or letting off the gas.
You have the cool head so you can go 4 mil if your crank isn't welded or you just want to up grade anyway.