I guess I'm weird; it depends on the bike. The stuff I most enjoy riding is typically more modern and I use what I like. The show pieces...I range depending on the bike. I am a good enough is good enough kinda guy...and if getting that last bolt means dealing with PBbikes, I'll do without.
I based this (blatantly stole) from one pogue developed.
0. - suitable for use as an explosive/pipe bomb. Also can be used "found art" and other such indignities. Bike may be referred to as a Lithuanian and you are permitted to play Creed near bike.
1. Suitable for outdoor beater storage. Put a chain around it, toss it in the ocean to anchor a boat, no harm done. Nearly any profanity may be used to describe bike, NSFW or not.
2. Hack, drew, saw away. Store under at least an awning or deck. No words used that would result in a YouTube video if spoken in public.
3. Eligible for powder coating, rattle can and art school projects, any weirdo configuration that can be imagined, but no drewing. Adding braze ons ok. No responsibility for saving original parts. Kept inside. No words used that would result in a slap.
4. Welcome to repaint in any way, including powdercoat, but some effort should be put forth to use decals if restoring. Tinkering welcome, original parts should be saved. Free to replace wheels with clinchers. Ok to add braze ons or coldset. Nothing worse than 4 letter words.
5. Some effort should be made to preserve paint when possible. If restoring, should be done with paint and decals should be done correctly. DIY jobs ok. Cold setting and hot rodding acceptable, but no adding braze ons UNLESS done by a prior owner. Changing to clinchers ok, must keep original parts if dated correctly. Use of whatever consumables desired is permitted.
6. Same as above, except repaint must be done by a person who has done 10 or more restorations. Allowed to see rain, but no salty roads. Bicycle should be gazed at fondly. Nothing worse than shoot or dang.
7. Repaints/restorations must be done by a professional. Hot rodding still permitted unless bike has 100% of date correct parts intact and in good original condition. Can still be ridden with modern clothes and lighting. Not allowed to ride if rain is 50% or more probably - unless you have fenders. Fenders still permitted to be after market. Must speak to bicycle as if it were a person.
8. Restorations only to be done by top pros. Restoration only permitted when threat of rust is significant. No cold setting. No hot rodding. Must use parts that look date correct to casual glance. May ride through puddles when needed, but care taken to use other bikes with chance of rain. May retrofit an old light with LEDs. Must use tubulars if spec'd tubular (or reasonably expected to be tubular). Duty bound to find "correct" parts when reasonably priced. Must lovingly caress bicycle before leaving house.
9. Every part should be correct, date specific and replacement bits must be as close to original as heroic effort produces. If part only available from absurd eBay sellers, plan heist. No killing allowed for bike parts. All consumables should be as close to original as heroic effort makes possible, including tires and tape. Bike must be re-greased, cleaned, waxed and fetishized at least annually. Storage space must have dehumidifier. Mood lighting should follow bike at all times...hire crew as needed! Must use Charleston Heston voice and/or Shakespearean dialogue when near bike.
10. Must be willing to commit mass murder for a barrel adjuster. If original screw is not available, must build time machine to acquire screw. All viewers must undergo decontamination and quarantine procedure prior to viewing. Must hire virgin to throw rose petals at front tire when ridden. Don't taunt bicycle, EVER. Must be kept in room where you sleep. Animals required to be sacrificed to bicycle weekly. Restoration only permitted to be performed within 10 miles of bike's birth and by original painter, or those descended thereby. If not possible, see time machine requirement. May not utter the word Shimano within 10 miles of bicycle. May only speak in Latin, Aramaic or Hebrew near bike.