600 Chainset

[Simon Head]

I have a vintage Shimano 600 chainset 42/52 which I'd like to use on my training bike, also vintage but very good in my eyes.
My race bike has been fitted with an FSA carbon chainset which has 34 inner and a 50 outer chainrings fitted. It also has 9 sprockets at the rear.
I'd like to duplicate the gearing exactly the same on my training bike, using 105 kit and New chainrings on the 600 chainset. Is this possible?

 

[Hugh Manatee]

Probably not. The BCD (diameter of the bolt holes) will be larger than the newer chainset.
The good news is that you can fit a 38 tooth chainring at the front. I have done this so know it works. That's low enough for me.

 

[Ajax Bay]

I'd like to . . .[fit] . . 34 inner and a 50 outer chainrings on the 600 chainset. Is this possible?

Your Shimano 600 has a BCD of 130mm and @Hugh Manatee has suggested the smallest chainring that is manufactured/available with that BCD. The rings on the FSA crankset on your 'race' bike have a BCD of 110mm (the latter allows rings from 33 to 50+ teeth).
Also bear in mind that I think you will have a 6 speed freewheel block to fit in the Dave Marsh frame. This has implications for chain width and therefore compatibility with chainrings designed for narrower (eg 9 speed) chains - they would still work, but not as well.