Richard
It is largely dependent on how particular (aka anal) you wish to be! For me, if most of the significant components are from the period, than that is perfectly fine.
No one expects you to use 50 year old tire, but its nice that they have a similar look.
For me, its the same with spokes and rims. I avoid the anodized things but happily use 1970's shiny aluminum rims on my 1950's bikes. The period rims are just too difficult to find, especially considering that I ride all my bikes.
Others, I feel sure will disagree. But its all what you are trying to accomplish with YOUR restoration.
good luck!
Ken Sanford
Kensington, MD
Ahoy ! The intent of the question is to hear the collective wisdom of the list, including of those who are dedicated to authenticity. If the frame is dated year "X", would it be considered an authentic restoration if the components were a mix of production years "X-1 year", "X", and "X+1" year ? This to account for on-hand stock, date of frame fabrication and actual build-up date of the bicycle. Thanks. Richard Cielec Chicago, Illinois; U.S.A.