Thanks for the replies.
@Bandera - It's a Forum, this is the medium for asking these questions. If baffles as to why there is always at least one responder in forums who's stock answer is, why don't you look it up yourself on the internet.
@nlerner & [MENTION=147177]BluesDaddy[/MENTION] - Thanks, these are great resources and I have used them a lot also but it's still hard to place some components in the overall scheme of things based on the info available there.

I do know that the further you go back the less groupset orientated it gets. I suppose the reason for my question was that, with modern components, 3rd and even 4th tier sets are perfectly functional for most riding and can even be raced on competently save weight weenie issues, but then there are lower sets that become a compromise to quality and function.

When selecting components for a vintage build, it's easy to play it safe and go with the top tier parts but in many cases that would be the same as going out today and buying Di2 or EPS for a bike only used for the Sunday club spin, an unnecessary extravagance, when 105 or Veloce or somewhere inbetween would be perfectly adequate. That's not to say that top tier isn't appropriate with the right frameset but for a stock non chromed or fancy lugged frame then mid-tier might be more fitting.

Maybe I'm trying to run before I walk, my knowledge bubble is quite good back as far as the late 80's but starts to get a bit fuzzy after that but this time last year I didn't have any vintage bikes and 4 years ago no bikes at all so prob just takes a little patience.