Peter.
I did once posess one of these machines and it was somewhat of a disappointment. I bought it new and found the spindle wasn't true to the table, possibly the same problem as yours. I contacted the dealer who came to look at it and agreeing it wasn't very good he offered a refund, or a replacement from the factory. I opted for a replacement but when it arrived, although better, it still left something to be desired. I kept it any way, probably a mistake in retrospect. In use the other problems were a very short quill travel, about 40mm as I recall, and no fine feed to the quill. This meant advancing the cutter using the Z axis feed screw, and the issue there was the difficulty in getting the head to move slowly and smoothly without any radial play. It wasn't bought from Myfords but a Myford fitter told me he'd had some experience with one and had himself found it impossible to get an optimum adjustment. Eventually it had to go. It may be however that despite these limitations it would be OK for your purposes.
I haven't heard any complaints about the FB2 so possibly that would have been the better option. At the time it was a close call but I bought the Rishton as I felt the Z axis handwheel at 90 degrees to the feed screw was ergonomically preferable to that at the top of the screw on the Emco.
I seem to recall that Tubal Cain made some criticism of the Senior milling machine not maintaining registration when the column was moved. I don't think round column machines are the best option for milling although a long quill travel and a fine quill feed would improve their utility. As on the the Dore Westbury, a machine designed by model engineers with model engineers in mind.
Michael