I have been wondering about a bigger pump as well. I tried to find info on the 1FZ used in forklifts but didnt find anything useful. I was thinking the forklift engine would probably have a pretty decent sized hydraulic pump mounted where our power steering pump is. From there the possibilities are endless.
I'm running a 365/75R16 (roughly 37 x 14.5) on stock wheels. On road the steering system has zero problem turning the tires. Off road I have to gas it from time to time, but mostly do not have an issue.
How much wheel backspace are you running? Wheels with a heavy offset seem to greatly increase the effort to steer the truck.
Hydro assist will solve this issue and also relieve some of the stress from the factory steering system and frame. It’s the cheapest and most effective solution to two possible problems. West Texas Off-road comes to mind.
So far the new pump I installed three years ago is performing satisfactorily with 37’s but it would still be nice to relieve some load from the factory set up in an effort to avoid a cracked frame, twisted sector shaft or broken pitman arm.