Based on your question it is not very clear what it is you are trying to accomplish. Do you have a 3 phase motor on the machine now? If you do you can swap it out for a single phase motor, or buy a rotary phase converter or VFD to power it.
RPM may be the trickiest to match. I'm not certain what ironworkers require. At least it shouldn't need to be reversible so that would make a 1ph conversion a little easier.
Still, I'd also look at RPC or VFD as suggested. If you don't want to build an RPC from scratch the "DIY kits" where you buy the control box and furnish the motor are far, far more affordable
I have a five hp. Three phase on it, someone had posted a single phase motor from Granger on a thread that was supposed to interchange, but I can't find that thread now. I was hoping to get lucky. I do believe I'll call Edwards, and see if they can help
One thing to keep in mind is that single phase motors have a large start capacitor or two on the outside, and sometimes that will foul inside the machine or in some way interfere with the mounting or another component. Make sure you have enough clearance for a larger diameter housing if you go the single phase route.
I would google five horsepower single phase motor and then narrow it down by RPM, frame, etc to match the same specs as the three phase motor. I'm sure there are many options for you and Granger is about the most expensive of all of them.