The northeast has not caught onto the Briggs LO206 category like the rest of the country. Many of the tracks are invested in other engine platforms, and have not seen the great package that is the LO206. The best bet is to get one, and go there, so people can see it first hand.
I know in NH, World Formula is a popular 4-Cycle option. The tracks like OVRP, LIKA, and Raceway Park are perfect facilities for LO206 racing. I would contact each directly to find out options if you go with LO206.
If not, Yamaha the next step up in the ladder system.