I agree with everone else so far. There are no problems with older bikes except maybe those that used cottered cranks-cottered what? Anyway in fact I believe from a newer bike that I have and all my riding buds in California where I use to live that my old mid 80's friction bike is more reliable then the newer stuff; considering that I have over 145,000 miles on the 100% Suntour Superbe components and the only problem I've had was last year the front derailleur binder snapped and replaced it with one I've had new in a box since 85; then I found another exact same derailleur new in a box on E-BAY so even the parts are easy to get!
Plus since the older stuff is friction they rarely go out of adjustment then the only adjustment you do is the high and low so the derailleurs can shift into either the highest or the lowest without falling off the gears or not making it onto the gears...simple! The single pivot brakes are also simplier and these even allow you to ride a bike with a slightly bent rim whereas the dual pivots won't. The older wider chains last at least 3 times longer then the newer thinner chains and their less expensive.
The older stuff is a lot more simple thus less to go wrong. You may have some problems with parts but E-Bay and some web sites have resources for most if not all the parts you would ever need.
As far as the wheels and fenders go, I'm not sure about fenders for 27's but I would assume that since 27's were made for a long time there would have to be fenders somewhere for those. Problem is due to road bikes geometry a fender may not clear either the forks or the calipers. I do know that when I switched to 700c wheels there are fenders from Planet Bike that fit my rig.
By the way the Suntour stuff you have even if it's middle grade stuff is still better in quality and shifted better then even the top of the line Campy stuff of that era!!!! And you got the top of the line? Superbe or Cyclone? Either one way out performed either Shimano or Campy or any other brand back in those days.
What brand of bike did you find?