Bad valve guide seals will NOT cause a lack of compression. The valve guides are up in the valve ports, whne the valves are closed there is no way for air to get from the cylinder around the valve guides. My best advice is to get a leak down tester. Connect it and turn on the air. If your compression is bad then it will be leaking air through some part of the motor. Either around the intake/exhaust valves, around the piston or through the head gasget. With the air on, listen to the different parts of the motor. Put your ear to the airbox, ear to the exhaust
, etc... and whever the air is coming out, that will tell you where your leaking.