Yeah, that should do it. But I have never been even mildly clear about how people manage to have as much trouble as they do.This is like "falling out of bed" easy. And yet there are pages and pages of hand-wringing and claims of days lost, data lost, lives ruined, etc.
One thing I don't think people get is that a Mac Pro can have any number of OS's and boot disks inside. I also don't think people realize that Disk Utility has a function similar to Carbon Copy Cloner with "Restore". So there is never any reason to EVER have any Data (or favorite OS install w/licensed software) at risk. NEVER EVER.
A 1TB refurb drive can be had from Newegg for $30. A Mac Pro can hold 6 @ HDs with ease. If you can't fit your Boot OS into 1 TB you probably take a steamer trunk on 1 week vacations. So, be smart. You have an OS install that has everything you want running like greased lightning but you want to move it to a newer OS? Create a restore image on a blank HD. Or just clone it and keep the original in a safety deposit box (or just not in your machine)
So, cloned/imaged boot drive is safe. YOU NO LONGER HAVE ANYTHING TO WORRY ABOUT.
Mix PPC Extensions from OS 7.5, Reinstall the Chooser. Do whatever you want to the OS and know you can just get right back to Point Zero with a few button clicks while you go make some coffee. So, now that we have removed any and all things to worry about, let's just pay really good attention to the things written by the people who have it working.
I personally think that the "build installer form real one in package editor" route is for people who have lots of time to waste and enjoy a Rubik's Cube that is missing a few panels. Someone you know has a Mac that runs 10.11 natively if you don't have one personally. Use Firewire, or SATA to USB or whatever, just get a full, solid install done on another machine.
Replace the 2 crucial boot.efi files.
I would recommend also doing the Recovery Partition. I wrote an easy way in the Mac Pro section.
I honestly and truly believe that some people form mental walls in front of themselves to keep life interesting. I awoke yesterday to 20 texts from an enraged customer. "Your card has an error and now my computer won't boot and I have a project due tomorrow and you owe me helping me" was one of the nicer ones. After hours of all caps screaming texts and emails he finally admitted that the issue had started RIGHT AFTER updating to 10.10.5, but only after I dragged it out of him.
He had to know, he hits "update", the 10.10.5 downloads and installs, computer won't boot on next boot. Nope, wouldn't admit that for hours of anguish until it got dragged out of him. Me, I'm thinking that it was such an obvious "cause and effect" moment, but he insisted there was a card fault, etc, etc.
Long story short, he wanted the fault to be mine so he wasted hours of each of our lives when he had to know somewhere in his head that IF IT STARTED AFTER UPDATE, UPDATE CAUSED IT.
So, I think some of the people who have been plagued by issues cut a corner somewhere. Hennessie says "Use a Blue USB stick" and they think to themselves "Well, my orange one hasn't given me trouble before, I'll use that and not mention it" and then come here whinging about "No Boot" symbols, and flashing question marks,and reboot loops. Ever since Tiamo did first boot.efi I have made multiple ones, never any issue. I can not for the life of me understand where all the issues come from.
Make a backup, and I don't mean copy a couple files elsewhere, i mean a disc image of boot disk, or an entire 2nd disc that functions exactly 100% like the one you are about to use/risk/ruin.
Pick one person who has made it work and who posts here a lot, and follow their posts, just theirs. Don't mix and match advice from multiple methods. More then anything, you need to realize that IT CAN WORK. You aren't climbing Everest for the first time. You are walking up a well lit path in a heated space suit with a guide rope, a GPS, and Helicopters overhead. If others have done it over and over, you can. You just need to NOT DEVIATE, no shortcuts.
I have always been a firm believer that if someone comes on a forum and says "I just used "Product A" and ran "Software B" and got "Result C" that they did it. People have very little reason to come lie about such things.
At this point I would wait 24 hours and see what results look like with the Final release. I'm sure other people will test before I do, I'm on West Coast and get up late. (And I'm going to be up late tonight) So, some of the Gurus will post what they did to get Final El Cap running. Do it.