Art, As Keith says, the best person to speak to or email is Ben Yates who now has either fitted or supplied about 80 coversions both in the UK and overseas.
As you know the Ace was originally announced as having R & P in the original sales brochure and John Bolster raved about the precision of steering in the first road test. I heard that either Bishop Cams or Morris refused to sell AC the Morris Minor system. This went into all Lotus Cars and other sports racers at the time, and Colin Chapman probably had his own ways of sourcing them. What is true is that AC acquired a "job lot" of over a thousand redundant old steering boxes. They were a pre-war design and went into all kinds of Austens, pre and post war, MGs, Wolseys etc. AC didn't run out of these until they had made about 60 Mark one Cobras. Alastair Caldwell, one time expert F1 mechanic and later Team Manager at Mclaren when Hunt and Fittipaldi won the championship and again at Brabham with Piquet, once said to me that even if AC had been given the Bishop Cams boxes, they must have lost money by the time they had made all the bits to make the lash-up contraption work and then done it again 100s of times. He has needless to say, changed his car.
It's possibly worth keeping the old steering with the car as it's easily put back. It's needed for historic racing in the UK and to satisfy any pedants. I had AE 43 for three years until I bought RS 5000 in 1970. When Ben's Yates/Tojeiro r&p was put in 9 years ago, I had no idea how nice an Ace could be to drive. I know now, and so do quite a few others! Speak to Ben.
A small indicator switch on the dash is all one needs. You can even get ones the "time out".
Good luck
Simon