Tripleizer chain ring And a longer BB or a 'Race Triple Crank, .... both Square Taper.. Campag /ISO BB
The 'Race triple' right arm is forged to use the same BB (111 for standard 115 for oversize seat tubes)
this is older parts , so good luck searching for them .. eBay, etc..
I'm Old

I got some when they were new..
extra <C> 30's to sell , I put 24t on my 50-40, and a 26 on my 52-42 ..
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