Help with tire/lift fitment q78 tires

[Madipie03]

Im looking at a set of q78 buckshots for my suburban I just bought. However im not sure what they will require for lift. They are a taller skinnier tire and with the right offset im hoping they will fit. The PO of my 70 k20 burb said hes pretty sure it was a 4" lift he put on it some years ago. Ive gotten mixed readings from measurements as far as hub to fender. Maybe the trucks and burbs were somehow slightly different. I dont think so. When I measure from the center of my front hub to bottom of fender I get 25 3/4 inches. The rear sits almost 2 inches lower than the front from the ground. So it sags and it already has a 2 inch block under the rear. Maybe it was a 4" and is wore out or? If anyone has a 67-72 with simliar size tires or buckshots please post a pic too.! Thanks