OK - Related to the Speed vs RPM

I converted my 65 to neg ground and changed the tach as Moss describes it.

Is it possible my tach reads like twice? I show 6000 rpm at 55 or so (my speedo was calibrated)

Don

Is there a perfered distributor replacement for a worn distributor when an external electronic ignition has been added?

Yeah Don, You're tach is showing about double what you are turning, but sombody that knows more about that than I do will have to tell you why.

Sombody will know the best year range, but it would probably be an older model with a quick advance curve.
If you go for a rebuilt get it from a bonified MG parts distributor. That's the only way you can be sure that the rebuilder knows what advance profile goes with which distributor. If your problem is shaft wobble you may be able to re-bush the housing and fix the problem. On a stock engine I doubt you'll actually feel any difference in performance no matter which distributor you use. If I were buying a rebuilt I'd go with the points type so I wouldn't be buying any expensive electonic gizmos that would just be wasted.