Well, I guess you did find the real reason a person needs the pedal assembly when doing an LB7/LLY to LBZ swap.....so theres that.
I'd totally forgotten how old school these 3 APP signal pedal assemblies actually were. The OG PPE boat actually had a LLY truck pedal mounted to the transom with a 33C control cable connected where your foot would normally go. The travel was so short on old single lever dash throttle control, ya couldn't shift F-N-R without blipping the throttle. Making docking or getting on the trailer a real pain. Back then I welded a 6" extension bar onto the foot pedal end, to decrease the leverage ratio, and add more travel on the far end of the cable.. Worked good on the old LLY.
Today, I only use these super slick non-spring return billet hand throttles, with [twin signal] programmable APPS built in. Also available in billet foot pedals, popular in air boats, or even cable adapter unit that works great with the old school controls. However, none of this new stuff works with those old school 3 signal APPS units.. But options for LS swaps and such have really progressed.