OK- - - -understood. As long as the M-II kit is from a reputable source such as the ones listed above, the load carrying capacity is determined by the springs the builder installs. The basic structure is usually "over-built"- - - -made of thicker material than the rest of the frame. The load carrying capacity and to some extent the ride height can be altered by using different height and/or coil diameter of the springs. A supplier of round track racing springs such as Racer's Wholesale, JEGS, or Speedway Engineering offers a pretty wide selection of coil springs with different diameters, heights, and weight capacities. Good luck!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!