if I am after a 5speed freewheel for my 1974 racer what should I be looking for to be authentic, what would have been the best flywheel for the time? (it will be running off a campy hub)

Freewheel.

And it would help if we knew what kind of bike you were working on.

Do you mean freewheel?

Doi

Yes freewheel sorry (if a mod sees my title please fix it). You can tell that I was not concentrating when typing. The bikes a Ron Kitching and I will be decking it out in period SR Campy components.

If it's a mid-seventies vintage Campy hub, the Regina Oro five speed freewheels would be correct.

There are loads to choose from. Is there a site that will enable me to tell what the packaging should look like for a mid 70s regina freewheel

It should look something like the attached, although packaging changed from year to year.

If you use a Regina freewheel I would suggest also using a Regina chain. Not sure why, but back in the day Regina freewheels worked best with Regina chains and all other freewheel brands did not like Regina chains at all. Would quickly begin to skip teeth. I haven't used a Regina freewheel in 30 years and modern chains may work just fine.

from a little googleing I am finding that there where a few regina freewheel options with the extra as the entry level is this correct?

for a Ron Kitching, a french Maillard/Atom 5 speed freewheel or an italian Regina 5 speed freewheel would be correct, depending on the hub's threading

ps- if yoy REALLY want to be period correct, a Milremo branded freewheel with the proper threading would be just the ticket. Ron was the UK distributor for many lines of French and Italian produced bike components and frames, many rebadged with his company's brand. His company was called Milremo , a cooperative trade venture between Andre Bertin, the french bicyle manufacturer and Mr. Kitching, who passed away just a few years ago.