Why can’t you use new rockers when you get used camshaft?

Only reason I ask is because I think I found a fix that may buy me time until I get a camshaft. Looks like the rocker arm is worn down as well, so instead of addressing wear in cam (~hundred), other side of the coin (rockers) is cheaper.

I added 1 new rocker arm to exhaust valve, and no longer getting back firing.

Thoughts/concerns?

Jub

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Current:
1971 Mercedes Benz 250 (Euro Spec)
1972 Mercedes Benz 250 (US Spec)
Past:
1972 Mercedes Benz 280