Coil springs: 1/2 vs. 3/4 ton?

[bud45]

I'm not "into" lowering trucks- I apologize to those who are!- but my '69 GMC has the same, original coil springs it came with. It doesn't sag at any corner, so it's OK, but I DO use it to go in the woods & go hunting and haul firewood, etc. Here's my question: will 3/4 ton coils work under it and would they possibly give me a little lift, too? Looking at aftermarket suppliers, there doesn't seem to be any, IF any, difference in prices, so...? Thanks, Bud