I don't know that you're going to get much of a choice, there aren't that many aftermarket cruises out there, that are suitable, especially if you have a cable speedo. Summit racing is about the only one I know of that still makes them. https://www.summitracing.com/search/part-type/cruise-control-kits
Never done it myself but back when I frequented YotaTech I recall seeing a few mentions of adding cruise, perhaps some of those companies are still around, I’d search their threads for info