talked to a steering box rebuilder.
he said the box ratio is generally controlled by the worm gear ratio
not whether it's variable or constant rate.
the early Pontiac GTO gear boxes, were like steering a sailboat
17:1 ratio from 1964-68
1969 had 15:1
1970-72 had 14:1 variable (16:1 center, 12.7 off center)
I have one apart here. it has a big tooth in the middle of the pitman shaft
that centers for high speed, straight line driving, i.e. highway cruising, drag racing
and gives high stability
the later "quick" ratios, were 12.7:1 ratio
all the teeth on the pitman were equal size
that makes it corner faster, but is "twitchy" on a straight line, as any slightest movement of the wheels or steering box, makes it dart or dive.
for drag racing, we're all better off with variable ratio
now the really interesting part
the lock to lock rating, is set simply the END CAP on the steering box
it is thicker, and stops the worm/piston inside sooner, limiting lock to lock travel.
otherwise it's the same darn steering box more or less
and that's not all
use a thick cap, to limit lock to lock turns, you lose TURNING RADIUS.
a stock GM GTO steering box has 87 degrees lock to lock on pitman arm
a later "quick ratio" or early Z28 box, only has 64-67 degrees
they are made for SMALLER CARS.
to use the thick cap, and short radius resulting from it, the car needs longer idler arm, pitman arm, and spindle arms, to recover some turning radius
the A-body G-body and full size, need a large turning radius
otherwise you need a 4 lane highway to do a U-turn, and it's K-turn city