In general 4 stroke engine tuning is a lot more forgiving than 2 stroke. You can certainly use EGT, and if Al Nunley is reading this he’ll tell you why it’s the best. I usually look at peak CHT for tuning 4 strokes with about 320 to 360 degrees Fahrenheit being optimum but you can operate within a pretty wide range and not be too far down on power, just don’t go above about 390F if you want the motor to live long.
If you’re just starting out though I’d set the needle about in the middle and you should be fine with stock jets operating in normal kart race conditions. You can read the plug for confirmation that all is well, it should be a nice tan color after you’ve run it a while. The WF is really a pretty straightforward engine to run and with regular oil changes should last a long time. In fact, the biggest benefit of these engines is that you really don’t need to spend hardly any time worrying about the engine and can concentrate on tuning the kart and your driving where the real speed is