Use a mono leaf. Drill the hole using the bit supplied with the smith bars (it's a blast drilling leaf springs) install and go tune. Pretty basic, I doubt that anybody here makes spring bending power so I wouldn't be very concerned with that. Top fuel burns a motor every pass so maybe we should stop using motors? It's the same concept lol.
I've seen both bars, yes the Smith has more adjustment. Do you need it? Are you actually going to try all of those combinations? That's for you to decide.