12 Bolt Rear End Advice

[rlehto]

I just picked up a 71 El Camino 12 Bolt code read CFC which should be 3.31 posi. I noticed the wheels didn't turn in the same direction thought it might be due to worn posi unit but I opened it up and it had 2.73 and was aa open rear end. I paid $500 so not to bad the guy thought it was open I don't know why someone would take out the posi and 3.31 for open 2.73?

Anyways few questions:

1. Before I took out the carrier the pinion and ring would not spin do I need to add some sort shims? The teeth look great they just seemed to be bound up when fully installed. I'm new to rear end stuff.

2. While I have everything out should I upgrade to a posi and a higher gear like 3.31 or 3.73. My application will have a LS1 with T-56 daily driver. Pretty basic maybe down the road add a twin turbo setup.

3. If yes to upgrading to the posi and gears wheres the best place to buy them? Also what else should I replace while I have it apart?

Thanks for the help.