Welcome stilllearning (you're in good company
)
The '79 Royale reminds me when I first purchased an S12-S ltd back then. Great memories of it as a 40 mile day commuter, weekend warrior to tour camping adventure rig. Gear inch wasn't even in my vocabulary either, it was all about getting on that shining bike and pedal away!
Older bikes are a hoot, and I still enjoy getting on a mid grade steel bike. But please, for that bike's sake trash that kickstand. Weight is obvious but more important to know, they damage the frame / chainstay. Also consider if it falls over, likely causes other damage. Much better to lean the bike on something or lay it flat, non drive side.
The Royale is certainly capable, and has excellent SunTour (Fuji label) derailleurs. Key is having comfy tires. Back then narrow tires were the rage for speed but lots has changed since then. Unfortunately the choice for decent 27" rubber is not much but the Pasela's seem to have catered to many. My game is hunting for vintage NOS 27 x 1 1/4 rubber on ebay and for near the same cost. Slim pickings but patience pays. For me, Avocet rank high and even the occasional score of Matrix Iso Tech 3K. For that bike I wouldn't spend much in going with a 700c swap, unless it was super cheap to near giveaway and without the need to do a brakes swap (if needed for issue of brake arm reach).
If you plan to keep it but want on an all capable rider, consider the following. I also realize that you've already changed the freewheel, but....
One thing you could do and make a climbing goat plus have big winding downhill gearing is swap to a 7 speed 13 to 34 Shimano Megarange freewheel. Usually found new for $15 or less. The hub's inside axle and spacer will need to be a slightly longer. Very easy swap but if uncomfortable doing it and you don't have the proper tools, have a bike shop do it. The threaded axle is usually just a few dollars or something to trade out from their junk bin. (Re-use your bearing cones.)
We're not done yet.... acquire a 32t or so small chain ring. You'd have to provide what crank that bike has and then either measure or look up the BCD in Sutherlands book. Chain will need to be lengthened. Lastly, not sure what rear SunTour derailleur it has, may or may not be able to handle the changed out gearing and chain wrap. I would at least test it, even if over the book specifications. But, should you need a 'long' cage type derailleur, get an older Suntour Cyclone and simply swap. Admit I'm sad to see those derailleurs getting out of hand pricey but ask around and you might find a donor.
It is kind of funny but its surprising on how well and capable a 26 - 27 lbs steel bike can be with just a few creative changes.