New, guy and kids. OR, USA

I havent ridden a dirt bike in years. My kids are getting old enough to ride so I got 3 bikes today.

2000 XR 70
2000 XR 100
92 KX 500 :) I know, I know

Thanks and done, I have been finding a wealth of good info here but I have some specific questions about setting my KX500 up. I am going to use it for play only and probably in the hills near where I live. So I am thinking I want to aim for low to mid power, Maby a headlight, a spark arrestor, handgaurds, skid plate (I don't plan to need one but don't want to buy a new case ether) I also have been reading that the compression of the kx 500 is a bit high for pump gas, would lowering it on the next top rebuild be advisable if I want to run premium? What reed/expansion chamber ect. will be the best for my use?

Thanks for any advice and input.

EDIT;
The FMF Q silencer seems right up my ally but They don't list it on there web site for the KX500. Any other suggestions? Can I modify the cr500 one (Welding and fab work not a problem)?