I believe that it is the same as the PSI Classic RB/FP.
Smitty had a variant made with an upgraded plating as a convertible RB/FP kit. Unfortunately, it did not catch on well so he discontinued it long before selling SPW to Exotic Blanks.
I don't know if he ever published instructions for it, but I think the PSI Classic instructions will work - not going to swear to it though.