I've ran 2.73, 3.23, 3.42's and 3.73's behind several engines in my Ventura.
With the 455 the best overall is the 3.42's teamed up with 28" tall rear tires.
Of course the torque converter is a BIG player with these things, and I have one of the very best converters ever made for one of these engines in place.
For freeway driving speeds you'll still find rpm's pretty high with anything much past 3.08's, but 3.42's with 28" tall tires provide acceptable rpms even at 65-70mph.
Here is the formula I use to compute engine RPM's at any given vehicle speed:
MPH x GEAR RATIO x 336 divided by TIRE DIAMETER.
If you have OD multiply the end result by the OD ratio to compute RPM's as that formula is for a 1 to 1 high gear ratio.......Cliff
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https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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