As m_c said - you need to know whats in there.

I converted my Bridgeport to CNC and I love it, made a good machine even more useful. Don't forget that when finished, it will still be an Omnimill - it will not take bigger cuts or drill bigger holes :) It will just do what it did a lot better and repeatably.

Provided the ways are not shot, it can be done. The ball-screw nuts are much bigger than bronze ones, on the BP they fit into a yoke that joins the X & Y screws under the table, does an Elliot have similar or are the two nuts totally separate?

The BP screws were 1-1/4" dia IIRC and the ball screws I fitted were 30mm - this made the nuts very large, a lot of conversions use 25mm screws so the nuts are almost the same size as the old bronze bushes. I ordered a custom made yoke built to fit which made the job easy.

30mm ball screws are very oversized i think as a BP can only take relatively light cuts anyway due to its flexible design, 25mm would be just as good as the loading figures on ball screws are amazing.

Stepper motors would work ok on the Elliot i think, servos probably overkill but nice still ;)