I think with drivetrain you’re asking for trouble!
Too many variables can mean once back on the bike it may or may not work properly. A rusty/dirty shagged cassette is still a shagged cassette even when clean, shifters wear out, rear mech jockey wheels etc etc. unless you are able to replace the key worn components e.g. small cog on a cassette; jockey wheels on a mech, you’ll get inconsistent results/dissatisfaction. Factor in that some of those parts on their own are either going to be unobtainable or financially unviable and it’s not worth doing.
Brakes - if you were able to offer correct new pads/shoes with refurbished/cleaned levers and arms maybe that could work and be less troublesome. Don’t know if I’d pay someone.
That said I’ve supplied bikes to folk in the past who are cash rich and time poor, happy to pay for my time knowing they get an old bike with new parts ready to ride.
Rusty shed finds are still out there just takes some patience and a keen eye! My best advice in that respect is always buy complete bikes, sometimes you can offset the price by selling parts, sometimes the missing parts cost more than the bike!
and don’t any of you bid on it now
