As you've had no response, I'll tell you what I think.
My VMC mill is slightly older than yours, so I'm unable to answer your question directly. However, if Warco say that the X-axis drive fits straight on, I'd tend to believe them. Mine is an Align unit and it, too, came with a casting for fitment to a Bridgeport. It wasn't used, of course, but the power feed was relatively easy to fit, so long as you observe the end-float requirements and use the enclosed shims accordingly. I'm really glad I got the power feed with my mill – it makes a big difference to the finish, I've found, particularly on long traverses.
HTH
John