That Johnson guy is simply an asshole. Use of the dumb rods all the time causes the compressor to work at least 50% more time. It's basically a ******** approach.
Guess what else, the rods do not allow you to fit that tire. Nor do they keep any of the problems from occurring if you lose air or are in full articulation. (Yes, it's possible I think he's an ******.)
I've been running 275/65-18 bfg and slightly larger for years now. The rods are 100% irrelevant. What allows the tires to truly functionally "fit" are the modifications to the body, frame, plastic fender liner, and rear hvac lines relocation.
So, there are many many youtube videos on strut replacement and air compressor swaps. The AMK is newer and just requires a dealer to reflash the computers I think. It's also a little smaller an easier to handle. The older Hitachi is still available but it's more $ and I would guess the AMK is better in some way.
https://www.roverparts.com/Parts/LR078650
The coli conversion will not make the tires fit any better either. You have to do the mods or reduce tire size. No magical way around it.