Ben, they are most likely Par46 bulbs. I can’t say what number bulb/wattage you need but the bulb you are replacing (or one of the other two bulbs in the Roto Ray) will likely have that info on it (printed on back). Gary Cahill sells a nice assortment of Par46 bulbs in a variety of colors through his website
https://rescuemarket.com/shop?keywords=par46&olsPage=search
If you don’t know exact bulb you need, Gary likely will as he has restored Roto Rays.
As for LED bulbs, I believe the ones used in current model are made by Whelen (earlier version look to be Tomar). They look very similar to some Par46 LED spot light bulbs Whelen sells (see attached pic). Might want to reach out to the Roto Ray maker for more info on those (have no idea if they are available directly from Whelen or if specially made for Roto Ray). Contact info in attached screen shot.