I have a 1946 3600 Chevy with a [1949] 216, stock 4 speed, and stock 4.55:1 gears in the rear.
On a flat, straight run, my friend tells me that I've done 50mph. My dad once clocked me at 47mph. (My speedometer doesn't work) I freely admit that I was pusing it a little -- but that was before the Tach, so I don't know how high I was revving.
Anyway...
My 4 speed has the following ratios:
1) 7.06:1
2) 3:48:1
3) 1.71:1
4) 1:1
R) 6.98:1
A 3 Speed from the same vintage will have the following ratios:
1)2.94:1
2)1.68:1
3)1:1
R)2.94:1
A three speed will make no difference in your speed; Your speed will be hiding in the differential. A 1946 3100 has a diff with 4.11:1, which can do 50(ish) comfortably.
If you'd like to go fast in your 'bolt, buy a half ton and get a ring and pinion kit. They make one that has 3.55:1 gears, which will get you about 60mph. If you want to go faster than that, then you're looking at either an overdrive transmission (like the T5) or a different axle (probably off of a car).
It's already been said, but it bears repeating. If you make it go faster, make it stop better, too. Upgrade those brakes. Really. You don't need to do discs, but definitely do
something.
Personally, I like the fact that I can pull trees with my truck.
