Its best to contact the welder manufacturer (if they are still around). The y've dealt with this issue in his area before. The local power company mig ht be giving you the more expensive route. Its in the welding manufacturer to give you the cheapest option (for service and other needed devices).
If that manufacturer is no longer around, contact a similar manufacturer of modern welders. Pretend like you are going to buy a new welder from them u sing the specs that you actually are on now. They'll probably tell you what additional devices you should install (any 60 amp breakers, xfmrs, sub-pan els, converters, inverters, freq drives, etc...) in preparation for your pu rchase of one of their welder set-ups.
The welding manufacturer might give you the lowest cost for other needed de vices/service not made by their welding manufacturing. They might even help to organize.