3.90 to 3.73 is not a significant change. I would suggest you find an RPM calculator on the internet and play with it. First you will need to know what tire size your going to be running. Then I'd find a rear axle ratio that would keep the RPM under 2500 and above 2000. I use 2.5k as the limit because that's about where the secondaries kick in on a Quadrajet, and gas mileage drops. Quadrajets are my preference for carbs. The 2k bottom is because the I think with the 283 you should be a little more into the torque curve than a larger sbc.

With the 4spd your options drop a bit for and OD. An OD would drop your rpm by 20-30%.

here's a link to the "Tech Tips" an a rpm calculator;

http://www.stovebolt.com/techtips/calculate_rpm_tire_axle.htm

LG

Last edited by LGriffin; 08/15/2009 3:02 PM.
I don't own a vehicle that isn't old enough to drink.