Any gains adding 1.6 rockers to stock 273?

Ok, once again to prove my ignorance of 273's......I see a few manufacturers selling 1.6 rockers. It got me to thinking maybe it would help my little motor breathe a touch more without actually having to open up the motor and change the cam.??

In all honesty, I have not yet actually measured the current cam to verify it is stock, and the motor paint looks a little to good to be original. But the lack of power has me leaning toward the idea it is "very stock". So until I get a spot open in the garage do some hands on inspection, I am just banging a few thoughts against the inside of my head.

Merry Christmas to all!

Scott