Throwing an update on this thread with some recent towing experience over the last year.
The tow vehicle is a '63 C10 Suburban, with the stock 230 six-cylinder, three-speed manual, 3.73:1 rear end, and two vital modifications: I swapped in the larger radiator from the 292/283 engines (although still on the stock water pump and thermostat), and converted the brakes to dual-circuit power discs on all corners. Probably could have just done the front brakes, but I hate screwing with drum brakes.... Those brakes give quite a bit more confidence, as I know they're not going to fade as long as I don't do anything strange. I also stayed with the 6-lug hubs when I did the brake conversion.
The trailer is an 850-lb, 14-foot, 2-axle aluminum car trailer with surge brakes on one axle, carrying a 2260-lb car and a utility box -- call it 3300 lbs all-up. Towing with the 230, weight management is important, and I spent some time finding a lightweight trailer to make this work.
Overall, the combination tows very well. Starting off the line with the three-speed isn't difficult with a little practice. It takes most of a minute to get up to 60, but once up to speed I have no trouble at all holding 60-65 on flat terrain and shallow grades. Steep hills would be a problem. The combination stops with no drama, wet or dry. Long steep grades are an unknown -- even with the disc brake setup, I'd be creeping down, and/or fitting electric brakes and a controller.
Depending on traffic, it may use a half to a quart of oil on a 700-1000 mile weekend, but I've had no problems with overheating (although my clutch foot sometimes gets mighty tired!). Overall, I've been very impressed -- although I have a larger engine and an SM420 that will eventually end up in the truck, for now I'm not in any hurry to change the existing setup.
