Greetings Marty
How is this going? I'm curious about how the 4.11 gear is working. I'm torn between the 3.42 and a 3.91 for my Tremec conversion on a 65 Wildcat.
3.42 is in the car and I'm about to try it out finally - started this in like 2003.
The difference in first gear will be noticeable.
Your 'First gear starting ratio' is 1st gear multiplied by the rear ratio:
2.87 first x 3.42 rear = 9.8
2.87 x 3.91 = 11.22
General recommendation is around 10:1 for a street car.
A 9.8 ratio is ok, might have to slip the clutch a bit to get the car moving.
A 11.22 ratio would get the car moving from a stop easier but it will be a short first gear.... you'll have to shift into second at a slower speed.
You're likely running tall tires which will affect the above a little.
At the other end, compare your highway speed/rpm to see which works better for you.
You have some other stick cars, so do that 1st gear calculation on those for comparison.