I don't know where they should be on your particular kart butt here's some general food for thought which may help you to decide where you might want to try them. In any case you won't know the outcome as with anything you try, until you test it out for yourself on the track.
General statements I personally consider ok:
Longer chassis lends itself to wider radius tracks and can help if your running high hp to put the the hp to the ground as in a dragster.
Another example is the reason why WoO and Allstars will run a longer chassis. They do so because acceleration during time trials is of the utmost importance to get them a good time trial time.
Shorter chassis lends itself to tighter radius tracks and a more responsive chassis.
Chassis longer on the outside and/or shorter on the inside lends itself to helping you rotate thru turns/turn.
A chassis longer on the inside usually is not a good thing for oval racing.
In addition to helping you rotate/turn making a chassis longer by moving the RF forward puts the RF into the track/turn sooner.
Shortening the inside length of the chassis or lengthening the outside of the chassis by moving the LR forward(as so obvious watching Late Models) or the RR back moves the center line of the chassis to the right. You can also think about it moving the nose of the chassis to the left. Again using Late Models for a reference you can think about it as moving the heavy engine weighted nose of the car to the left hanging it out over the inside of the tracks banking.
All of the above are to change how various tires will interact with the track. Yes they all will change weight outs but more importantly they change the way each tire will work with the track. They are physical changes to the chassis and even if you put your weight outs back to where they were as I suspect most offering help on here would suggest, they still change how your tires will work with the track. Because of that besides learning what each will do to your karts on track performance, will also build your arsenal of specific things you can do to fix specific on track problems.