26.4mm or 27.0mm Crown Race for 1987 Cannondale / L.L.Bean ?

[TANGE]

Hi, I would like to replace the headset on my 1987 Cannondale / L.L.Bean... What crown race size should I get?

 

[black lightning 1987]

I have two Tange forks here that are both 26.4. One is from a 1987 R600, not sure about the other.

 

[TANGE]

I have two Tange forks here that are both 26.4. One is from a 1987 R600, not sure about the other.

Thank you!

 

[black lightning 1987]

I guess that I should have said that if I were ordering a new headset for that bike without measuring, I would order an ISO headset with the thinking that it is the most likely size. Have been wrong before though. My 1993 lugged steel Specialized Allez uses a JIS headset.