From the photo I can't see any reason to respray it and many good reasons not to. At the very least, it would surely be a good idea to first treat it with Kurust where needed and touch in the chips etc and see how you feel about it then. It would be a shame to lose the authenticity of the original paint and decals unless it was really necessary. But not forgetting that it is for he who has paid the piper to call the tune of course!
I'm fairly sure it isn't a 1991 frame. Most likely 92, but possibly 93. If you're interested, we can date it from the serial number under the bottom bracket shell.
Clockwork frames are seriously under-valued in the marketplace considering how good they are, but even by normal standards you've got yourself an excellent bargain there.