are there really any rules for what we consider a classic or vintage bike?
1999 Waterford. full Reynolds 531 frame lugged wit a 1” fork. no down tube bosses
most folks would say it’s a typical 80’s era bike.
I would say Classic, I think of vintage as drilled out components, bar mounted bidons and tyres around your shoulders.
I' am in the middle of a similar build with a Masi Special Ltd, OS lugless with 1 1/8" but the effect using some rules I arrived at has made a massive difference to the original modern fixie appearance.
1/ Alloy or polished finish: get all the colour off. Blackened components didn't really take off until the 90's (hard anodised rims the exception)
2/ Thin: Rims (15mm profile max.), Cranks (defined arms, no heavy spiders), spokes (std or DB), Bars (26mm max. no large dia.), Brakes (DP ok but thin profile.)
3/ Solid colour: seat, bar tape and cables preferably black or white but brown, silver or other that works ok but definitely single solid colour.
I thought originally the oversize tubes and steerer would be a problem but the component choice has reduced their visual impact.
Thin appearance/profile and alloy/polished finish is the key.
Oh yeh, if you are ever going threadless use a 17' stem, nothing kills a classic look like having the bars sticking up in the air.
Good luck with the project.