How much wire feed work do you need to do? Because you can also just use a multi-weld converter... they are pricey as well but work a bit better and can be rented from Redi-arc.
I cant say for sure on that one, If you have the model-code from a newer SA-250 and an older one you might be able to download the manuals for both and see if the cv option has the same PN Tom