You can run pretty much any front gear you want.  No clearance issues.  The rear gear might be an issue depending on what chassis you are running.  If you are running anything over a 70 tooth, you might have lack of clearance at the chassis cross bar.  Especially if it is a 2 cycle chassis.  I would ask around about what ratio most people run.  Find the gear combo that will allow you to run a rear gear in the low to mid 60t range and you probably won’t have any clearance problems.

I am not familiar with your track, but I would start with 15-18 driver. That will get you in the ballpark. I did use a 19 a couple of times last year, but those were special cases and you could get away with an 18 and a smaller rear gear if you had to. On the rear, I would say 60-65 will get you started and slowly spread out from there. Look for gears in buyouts and at swap meets. You can find them super cheap.

Keep in mind a 1 tooth jump in front is roughly equal to 4 teeth out back.  Gearing will be dependent on the longest strait, slowest corners, and driver weight.  If there are several tight turns you might have to gear so you are on the limiter a bunch on the long strait.  Won’t hurt the engine to do that.  You will just need to get in the ball park and test from there.  You might even need to change gearing as the track changes throughout the race day.  If you can find the high mph of a LO206 at your track, you can use a speed calculator found online to get you pretty close.  They are base off your gear ratio, rear tire circumference, and the max rpm of the engine (6100).

FYI…I have a near complete set of split rear gears (only missing a 62) for 35 chain along with a bunch of clutch gears as well.  Also a 35 chain breaker and several master links.   Gears are a mix of new and lightly used – front and back.  Check out my post under parts or email me at tuftsrich@gmail.com.  Good luck.

For 206 at most tracks 15-19 will have you covered. I would not go smaller than 57 or bigger than 62. If you get out of that range you need to change the front and start over. This will allow you to keep engine spacing consistent and not make it necessary to cut or lengthen your chain.