Sounds good so far...
Gear ratios are one of those things that each person chooses to enhance what they want their own car to do for them...
IE- 3.90 may be good for the drake but may be totally worthless to you if you want to travel with the car....
Picking the ratio that makes the car it's absolute quickest for all the parts you have in the engine and trans MAY not be always the way to go. You may need to compromise to maker the car do what you really need it to do.
SO the million dollar question- WHAT do you want from your car? What do you do with this car? or what are you GOING to do with it?
burn outs light to light action hang around town like drake or are you going to do hot rod touring across the USA ??? Really think it over.
What I see right now is - lack of a starting ratio- WE need that ratio that is in your 10 bolt rear first then we can go from there because right now the ratio could be 2.56 2.73 3.08 or 3.36 these are the MOST COMMON gears they put into the A-body cars.
You have a 3 speed auto tranny - so you have a good low first gear 2.52 - This will multiple the ratio 3.08 making the rear feel like 6-7 to one on the launch. But in the end you will need to drive the 3.08 ratio once in third gears also know as 1 to 1 when your in 3rd you are driving 3.08 to 1 ratio.
Next thing you have a 2600 stall meaning the convertor will not hit full efficiency till 2400 ish this is where the car RPM should be keep for best mileage and least amount of slippage in the tranny.
Your tires are about 28" tall so as stated in the post before you have plenty of tire to support more steep gears like 3.55 or 3.73.
IF your rear has 2.73 in it and you think it is doggie then I would bump it up to 3.36 area
If you have 3.08 ratio maybe bump up to 3.55
if you have 3.36 and you think it feel doggie then 3.73 might help you out.
REMEMBER - there is NO substitute for a well tuned carb and ignition on the engine to give you snappy torque and gas mileage and power. This is why electronic fuel injection works Sooooo
well.
Jim
Please keep the questions coming if you need more help.
The extra help by other members is ALWAYS appreciated, Thanks to you all-