Stop by an electrical supply store that caters to the trade. They can tell you what the prevailing electrical code is in your area and what is available. There are plug and socket combinations for things like construction trailers which don't typically get hard-wired. Or wait awhile as there are many electricians on this board that can quote NEMA part numbers. I am an electronics engineer which is NOT an electrician so I would go with their guidance.
That said, Vicegrip nailed it IMO. I run a welder that is intended for a 50 amp service off of a 10-3 feed which is permitted where I live. If it was a standard service it would be rated for 30 amps. The code treats welding supplies more leniently than the usual service uses. I would put money on it that a NEMA 6-50 plug/socket combo would work just fine and they are stocked at Lowes and Home Depot.
Harris dual-stage O/A
Lincoln AC/DC buzzbox
Hobart IronMan 210
Lincoln PowerMig 135
Miller 3035 spoolgun
Thermal Arc 185
Thermadyne Cutmaster 52
Angle grinders, vicegrips, the usual suspects
Two hands, tired body, not enough time...