You should be able to create the modified usb Mavericks installer on a Mac running Snow Leopard or newer. Older if you already have the mavericks app downloaded.I'm sorry, maybe this was mentioned somewhere or was otherwise obvious- but what OS are you guys upgrading from when you run this installer? Can you run this from Snow Leopard or do you have to be running Lion?
I'm considering starting over with an SSD as a boot drive and was wondering if I could just install SL on the boot drive, put the Mavericks installer in the Applications folder and run this script.
For installing onto the Mac Pro 1,1/2,1 then it shouldn't matter what is currently on it, I installed onto a completely clean system with nothing on it.