How's your mechanical skills? What's your budget for ongoing maintenance (both time and money)
The Dura-Ace of 20+ years ago will be 6-7 speeds at best, with a double chainring, and will be a lower technical level than the more recent but lower specced Sora. Depending on how the bikes have been ridden and cared for, either could be a clear winner.
BTW brifters are much more fun to ride than thumb shifters or downtube shifters.
As for brakes, dual pivot Dura Ace should be better than single pivot Sora. Three major things that cause bad braking are non-true wheels meaning the calipers have to rest further apart, dried out brake pads (replace them with Kool-Stop ones) and mucky cables/housings. If you're mechanically inclined this is all stuff you can do.
Frames - if the Raleigh is truly a carbon frame, inspect it up close all over before buying. You're looking for any damage or cracks or chips that aren't simple paint cracks. Use a bright torch and a magnifying glass, and don't be afraid to walk away.
Source: I recently bought a 1997 aluminium Mongoose road bike for $123, and then spent over $200 on replacing the worn and dodgy bits. But its awesome fun to ride fast.