Flaming River and PST Fast ratio kit?

No, don't combine the two. The standard Mopar manual steering box is 26:1, and some people consider that heavy going, combined with wide tires. The Flaming River box makes it 16:1 -- so that is faster by a ratio of 1.6:1, but also requires more effort by the same ratio. The PST kit claims a 12:1 ratio with the standard steering box. Add that to the 16:1 box, and your final ratio would be less than 7.5:1 -- only a little more than 1 turn lock-to-lock. Go-Kart steering is not going to work with 1800+ lbs on the front wheels. You probably wouldn't be able to turn the wheel at all when stopped. I think the 16:1 box will be plenty quick.