Your best bet is to grab a cheap junkyard core and have at it. Building a rotary pump right isn't easy though, and the correct way to do it is to have one of those(expensive) calibration test flow benches Mel showed. There's a guy on the 6.2 forum, dieseldummy, who's messed with the 6.2 pump, he doesn't claim to be an expert but he'll tell you what worked for him. My advice is to get pump or two that are cheap and if you completely ruin them your feelings won't be hurt too bad, and do your homework and learn all you can about them before you even think about putting one you built on a truck. Probably the worst risk you're taking is that a home rigged pump might be so far out of calibration that you could cause the engine to run away when you start it back up. Be aware of what you're risking and at least have a secondary way to shut off the engine before it commits suicide. A solid hard bound book or smooth clean piece of plywood to clap over the intake. A shop rag or beachtowel won't do it. If it does run away it will scare you senseless. Be careful and take it slow and easy. I have never built an injection pump, but man would I love to learn how to do that stuff right. People that can do a good job are in short supply as are really high quality reman pumps, which is why people are willing to pay a premium for the Moose.