Original 707-420 Rolls Royce purchasers were BOAC (the majority), Lufthansa, Air India, Varig, El Al and British Eagle. The last one came at the end of 1963, to Varig, they all then moved on to P&W versions.
Comparable DC8-40 Rolls Royce purchasers were Trans Canada (later Air Canada), Canadian Pacific, and Alitalia. Again they all moved on to P&W. Production of these lasted until 1965. Douglas had a shot at re-engining a couple they had been saddled with as trade-ins in the 1970s with P&W engines, but not a successful programme. Probably too expensive.
They all became dogs on the secondhand market, being so non-standard, and many were retired when finished with by their original owners (the BOAC fleet passed on to BEA Airtours being a notable exception). You will also notice that production finished just at the time that VC10 production, also powered by RR Conways, was starting.