I know Bill and Will and have raced with them on many of occations. I used their 5 speed conversion kit for my sprite using the nissan 210 5sp. The car was a blast to drive on the street but the gearbox just couldn't handle my hp in racing condition. With 170hp, the only gearbox I could find that would not break in a season was from Jon Stamps Racing built with the nascar style(Richmond gear set)dog ear gear enguagement with ultra close ratios designed for road racing. Not fun for the street though. 1st gear is good for 80mph to make for a very slow start from a stop.
I think that kit, installed properly, would make for a great street or race application with as much HP you can give it without failure.