Please some info regarding IFS kit's

[mr48chev]

I agree with the multi leaf springs if you are going to tow that heavy a trailer.
I'd also suggest leaving room for a pair of air bags above the axle. Not to do the frame scraping thing but to be able to level the truck with the trailer attached and stabilize it. The other option and maybe a better one would be something on the line of an eazy lift hitch setup to distribute the load and help control the sway of the trailer.

I used one to tow the 15 ft travel trailer I had behind the 48 and it helped keep things under control.