You can only repair a nitro finish with nitro, you need to polish it afterwards and for this you need special equipment and a load of know how. Your XR-1 is from the early 80's, it does not have high collector value and players will only respect it for having a few chips because that means the guitar has been used.
I have 'sealed' a rather nasty bucklewear patch on one of my guitars once with nitro, just to prevent it from drying out and cracking, this was a large patch though, small ones wont affect the wood mostly.
If you are really determined to try and really mess this guitar up, because trust me, it will look worse if you start messing with it, do so with a bit of nitro and a VERY small brush and try to layer the nitro very carefully and giving it plenty time to dry. DONT sand it or anything, youll mess the surrounding finish up, nitro is very soft.
The stories on the web of people reparing chips with nail polish or even superglue are from idiots, dont believe them, putting agressive solvents on a nitro finish, or even worst, dissolving agents like thinner or nailpolish remover will make you insanely mad of yourself because it will completely destoy the nitro. Those are the same people who spraycan attack old fenders, they dont understand anything about a guitar.
The only option i can think of is asking a luthier to repair it, like you said its just a few spots and i dont think it wouldnt cost that much.
