You don't say how you want to use this truck. If you are going to haul heavy loads with it I would not be too concerned about spinning a 350 at 3000 running down the freeway.
With an HEI (started in pickups in '75 I think) they will turn way past 5000 and they have a good pressure oiling system and a valve mechanism that can handle turning fast.
2000 to 2300 is fine for a light empty pickup.
My 1-ton pickup with 4.11 gears and 31 inch tires runs down the road just fine at 75 or 80 even pulling a trailer. At 65 its turning about 2900 at 75 its about 3300.
Empty thats a bit of a waste, but loaded I appreciate the power it makes turning faster, and this isn't a 350 its a 454.
The smaller your motor or bigger your load the more important gearing is to performance.
From what you've said I wonder if chasing a ratio change is the right place to start. You may want to spend more time determining why its noisy and riding like a camel. It may be the ratio change isn't going to fix the problem, but will eat up some serious money.
