My '89 Suburban has 350EFI/TH700R4/3.08. I thought it was a pooch so I massaged a few things in the engine. It's no barn burner, but it is much nicer to drive now. Sounds better too. Also added a rear anti-sway kit and huge trans cooler.
I pulled the '47 ton dually panel, on a trailer, (total weight approx 7500 lbs) 600 miles to get it home. It worked it, but I just stayed out of OD, kept it down to 55mph and avoided stopping where I had to take off headed uphill. The 1/2 ton suspension caused me more stress than the powertrain. It was definitely floating. The key is to take it easy.
If you don't like the way it pulls your trailer, think about adding some snort to the 283. Or better yet, look around for a 350. That 283 should sell for enough to pay for one.
You could also consider regearing that 2.73 to a 3.23 or 3.54. A ring and pinion isn't all that much, but the GM rear ends are a little tougher for an amateur to get set up right, so you might want to get a pro to mic it all out and do the final adjustments.
BTW, The fuel mileage actually improved with the modifications I made to the 350. Best I ever got was 18 mpg highway. I hope I can get the panel set up so well!
