Hmmmmm. Before doing anything, try the exact same arrow in both bows and see how it shoots. It just might shoot well out of each of them. Generally, because the longbow is less efficient (if it's a longbow and not a hybrid) than a recurve and because it's cut to center, but not past like the recurve, you'll need a longer arrow or more point weight on the arrow intended for the longbow. (You have it backward.)
If your "longbow" is a hybrid, it's likely to be about as efficient as your recurve. Then you only have a 1/8-inch difference in center cut to deal with. If that's the case, you might be able to achieve the same arrow spine, length and weight for both bows by building out the side plate a bit on the recurve.
I'm also assuming you have the same string material on each bow. If you have dacron on one and low stretch on another, additional modification might be necessary.
You'll just need to experiment a bit to find a combination that works. God luck.