rear end questions...

[scuderia]

Looking to swap out the gears on my truck.
Currently has the original 12 bolt non-posi rear end. (suspect it's 4.11's now but haven't pulled the cover to check.) Anyway, since I'm running a granny sm465 I'm figuring that I can go with some pretty tall gearing 3.07 or 3.08 (what's the story with those two? why are there both out there). I know I need a new series 3 carrier as well but what exactly 'am I looking for with regards to years, models etc.
Also, I'm running a 292 at the moment but will eventually be putting in a 327 anyone have thoughts on the gearing choice? I know that there are 3.42's but I'm doing more freeway than I thought and I'd really like to be able to cruise comfortably at 70 with either motor (28" tires on the truck).

Don