I didn't want to be negative, but I thought that 5 inches of blocks was to much.
4 inch blocks is about it for a 521 truck, with them one really needs to use aftermarket rims to get the clearance needed in case of a flat using 510 wagon shock mounts.
To me it looks like 3 inch blocks is about the max for you, perhaps you can find or have made de-arched leafs, I cannot see your rear shackle mount, maybe some mods can be made there to lower it like I did to my 520 project.
These are roadster shackle mounts that I bolted to the frame, it's around a 4 inch drop at the shackle, but it around a 3 inch drop at the axle itself, I would never use these on a truck that was for hauling weight, but as a looker it has been fine so far.

Here is the difference on the truck with a tape measure.

“The difference between genius and stupidly is that genius has its limits” Albert Einstein