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That's not your problem. The LSPV doesn't control front brake pressure, just rear brake engagement time and pressure.
Once you have the brakes bled/sorted out you want to start with the valve as high as it will go and see how your rear brakes feel. You may need to adjust it down some, every truck is different. But starting at the very bottom will probably cause early rear brake engagement.
I've done many of the frame replacements under recall, so I've had plenty of experience bleeding these brake systems from scratch.
Gravity bleeding is your friend when you replace brake parts. Especially long lines. You can also give the brake pedal a few pumps before you open the system to help force fluid through. And while you're at it, it's a great idea to flush the brake system at the same time. You're already doing half the work anyways. On an old truck it's a good idea to go back in a month or so and reflush, to get rid of more of the crap in the system.
If you're still getting air through the LSPV, you probably have a leak.
If you're getting air through a bleeder and can't get rid of the air, you have a leak. It doesn't matter what order you bleed them or if the lines are hooked up wrong. If everything is tight you WILL eventually get everything bled. Your brakes may not work right [if you have the lines hooked up wrong], but you should still be able to bleed them.
Bleeding in the wrong order will only slow you down, it won't stop you from bleeding the brakes. Don't get me wrong, you should do it in the correct order, and it will get done faster, but it's not 100% necessary to get the job done.
If you're not getting any fluid out of the calipers you may have clogged up bleeder screws. If that's the case you may get lucky by just removing them and cleaning out the port [replace with new ones if you can find them]. Otherwise you'll have to replace your calipers.
You also may have a bad master cylinder. They tend to go when the system is drained and someone bottoms out the cylinder pumping the pedal on an old system.