Your ignition switch could be worn out. If you have a wad of keys on your key chain the weight of it wrecks the switch. I think it was $35 10 years ago at toyota when I replaced mine but it was also available at the auto parts store too.
I believe the problem is that it transfers all the engine twisting torque though the case plus has the stress of all the weight on it. Basically it changes the way the load and torque goes through the case. I'm not a fan of the design but haven't had one.
Bias swampers are great off road. They're noisy, pull and go lumpy if the truck sits for long, especially in the cold but I think those are a small price to pay and isn't why you buy them. I have never owned radial swampers but have never been impressed with what I have seen on the trail.
You did the right thing grinding a little off the ring gear.
You will end up with negative antisquat if any. This will cause the back end sinks as torque is applied to the rear axle. There's lots of reading on this subject...
You better move that axle way back or weld the rear doors shut. Maybe its just me but 46" tires sounds really ambitious for those axles, especially punishing leaf springs with them. Don't even think SOA like Mace said. I usually wouldn't jump on the link band wagon but with any tire close to...
flat springs is what you want. You can always pull the AAL though.
It looks like you will have to trim the rear of the wheel well opening even with the 35s. You will just have to try it out and see.
Get those shock towers off there and buy some Ford ones!
The springs will likely settle at least an inch the first bump you hit even with the extra leaf. Why did you add a leaf? Its looking like some trimming will be required...
With my SR and SOA on flat springs the shackles look really close to the frame, probably less than 1/2" clearance but there is no evidence of contact on the paint on the bottom of the frame. Your springs ok, they will flatten out as you add the rest of the body and the springs settle.
wow, this really hits home on many levels without having experience in the same way.... I've lost friends way before their time but in horrible and unexpected circumstances, not like this. I read the story on pirate as well and its great that you have done this for him and his family. Please...