1948 gmc 3/4 ton rear suspension

[1948GMC]

I have a 79 trans am 3:42 posi rear end and have the stock springs and axle in the truck but ant to take that out and put the 79' rear in it. I need help figuring out what to do with my suspension because I don't really wanna go 4 link unless I have to. I would like to stick with leaf springs but the only ones I can find will fit 1/2 tons and I am wondering if just taking the helper springs out of the stock springs could I put the rear end above the spring without notching to lower it? I would like to lower it atleast 4 inches. Thanks