Ok so I pulled two 4awg thhn cables (two hots) and one 6awg thhn cable (ground) in 1" aluminum flexible conduit. THHN cable is almost 1/3 the price of regular NM B cable and rated at higher amps but it has to be ran in conduit or cable tray. I measured the required cable run at 53ft but ordered enough cable to run 70ft to prevent having to install a splice box. Installed a flush wall 2 gang metal box and used flex connectors to connect the flex conduit to my main panel and the metal box. I installed a 100amp double pole square d breaker in my main panel and a receptacle rated at 50amps in the 2 gang metal box. The receptacle is the weakest link but it was either that or dish out another $300 for a receptacle rated at 100amps vs $12 50amp receptacle... hence the metal box and metal conduit. For whatever reason if I am running the welder wide open for a long period of time and the receptacle starts to get hot it will not damage the metal box. And because the flex conduit is mounted on each end (main panel and metal box) the flex conduit is actually a second ground. Instead of putting a regular wall plate for the outlet I installed a metal outdoors cover. The receptacle is in the garage but I wanted to protect the outlet. Also I leave the breaker open and only close it when I go to weld. It really was not that bad of a project, the hardest part was pulling the cable through the flex conduit.