suggestion on springs

[clutchcover]

I have a two wheel drive 59 Ford F-100. Right now it has some weird aftermarket springs on the rear from back in the day. I am curious if anyone knows the ride difference in the 1/2 ton and the 3/4 ton suspension. The springs right now are really heavy, and very worn out and flat. I have 3/4 ton springs up front due to a larger big block engine and they seem to work well with the weight, but with no weight in the back I am worried the f-250 springs will be too heavy. I occasionally carry semi heavy things in my truck, but do not want to sacrifice ride quality. I have a good spring shop here, but the guys doesn't have any experience with 57-60 for trucks. He'll order or make me anything I need, but he needs to know exactly what I want.
Also, has anyone had a bad experience with Holley products lately? My family has run them for years without incident, but this is the third carb of the same model on my truck. They are replaced under warranty, but each one has had a different problem due to a manufacturing defect. I love the way it runs with the carb, while it is working, but it gets old replacing them every couple of weeks. Just wondering if someone else has had any problems.