Offset shackles
It's totally splitting hairs, but I was able to get 5/8" by cutting off that small piece of overlapping metal where the rear subframe rail meets up with the piece where the front spring mount bolts to (red arrow below). That was the limiting factor on my '68 - not the rail itself. I also notched the frame slightly to allow for the bolt head. All-in-all, it ended up being plenty for what I was doing. The 275/60s don't rub at all.
Lots of kits and lots of ways to skin a cat with this stuff. In the end, it just depends on how much cutting, welding, and grinding you want to do.
*edited for additional detail
It's totally splitting hairs, but I was able to get 5/8" by cutting off that small piece of overlapping metal where the rear subframe rail meets up with the piece where the front spring mount bolts to (red arrow below). That was the limiting factor on my '68 - not the rail itself. I also notched the frame slightly to allow for the bolt head. All-in-all, it ended up being plenty for what I was doing. The 275/60s don't rub at all.
Lots of kits and lots of ways to skin a cat with this stuff. In the end, it just depends on how much cutting, welding, and grinding you want to do.
*edited for additional detail
