TruTrac if you're going to keep the car and 3.73.
I'm planning to keep the car forever, it has too much family history. I'd sell all of my other cars first and walk before letting it go. Because of this I'm willing to spend a little bit more on doing it the correct way. Some people direct messaged me and asked for more details (I hate it when people doesn't provide enough info, I should have done better).
The car was pulled out of a barn 2 years ago this Easter where it had been sitting for 20 years. The motor and trans were in really rough shape. It was restored in the late 80s, so I've gotten it back on the road, cautiously spending money only where necessary. The Powerglide was really struggling so last winter, it was replaced with a KZF 200-4R from an 86 Olds 442. The 200 really woke it up. Now that it's a reliable driver, I'm looking for ways to improve it while keeping/returning it's tame Malibu aesthetic.
Block casting is 3914678 from 1968
Head castings are 3782461 from 1964
Cam is unknown
Intake is Weiand Single Plane - 7546
Carb was a Carter 600, now a Holley 750 but just purchased a new Holley 600 cfm.
Eventually I'd like to do a vintage motor, looking like stock 283 but with hopped up parts. From what I hear in everyone's comments, you don't like the current motor combination, and I agree.
Here's where the thread is at.
1. 3.73 gear for the back is going to help the transmission a lot.
2. LSD for a 8.2" 10 bolt is difficult to find.
3. If rear gear doesn't fix the problem, install a switch for lockup.
4. There are 100 different ways to do something and it will be difficult to get a consensus.