Good morning,
I am not a dedicated/enthusiast restorer but I did buy a used 531
Ribble quite a few years back as a commute to work bike (17 miles each way) and over the next few years replaced;
Wheels, tyres and tubes
Cassette
Front Mech and cables
Rear Mech and cables
Downtube shifters
Chainset
Pedals
Front and rear brakes and cables
Brake levers
Leaving
Frame
Bars and stem
Saddle
Bottom bracket
as the items on the bike bought.
The Ribble came with friction shifters that slipped all the time so I ended up with Tiagra shifters that were indexed only, and as the rear mech preceded the indexed era and had the wrong cable pull it had to be replaced.
The front mech had the cable clamp thread partially stripped and the chrome was peeling of.
I suspect that the brakes and wheels were put on the bike to sell it as spoke tension was all over the place, the rims were heavily worn and the brakes were longer drop than ideal and couldn't put the whole of the pad onto the rim.
Both chain rings were worn and replaced, then a pedal broke and I got bored trying to remove it so bought a new crank, as this didn't match the other crank ended up replacing the whole chainset.
The cassette was 7 speed and I was finding it hard to get 7sp cassettes with the right sprocket size.
Only the brake lever change was a vanity change as they did work but were horribly scuffed.
So a new Specialized Secteur would have been a better buy and I came to the conclusion that old and heavily used bikes were not projects for me.
Even this bike meant that I had to buy a more modern cassette removal tool, if you have a toolkit designed for Hollow Tech BBs era you may need to do the same and go backwards for older BBs and possibly Campag/Shimano cassette tools depending upon what you buy and what you have.
If you get modern and get one of the first STI equipped bikes then like me you may end up changing some components to be compatible with others as there were a few changes in cable pull between non index, indexed and STI indexed components across the ranges and times.
Bye
Ian