F-body steering box?
The F-Body steering gearbox will work, the Buick Grand National box will work and the Monte Carlo SS box will work.
The various boxes have different steering limit stops...Meaning and F-Body box may only be able to turn wheels 32 degrees. This means that you may have to do a three point turn, whereas a Typhoon/Syclone box has a 45 degree range, meaning you could do a 180 in less space than the other type box.
You need to use the pitman arm from the truck, not the car.
Lee Manufacturing and AGR make great steering boxes for these trucks, but they are expensive.
On my '93 Typhoon, I used a Lee Manufacturing box. 12 to 1 ratio, medium spool (effort) and it had stops to limit the range to 42 degrees. This kept the tires off the inside frame rail at full lock.
I've used the Monte Carlo SS box on a 5.7 TPI Blazer, and I'm using an AGR box on my Magnusson blown 6.0 2000 S10 Blazer with Auto trac 4-wheel drive.
Phil