273 rocker arm limits
In the 80's I had a 13:1 comp 340 with a .585 lift cam & Crane triple valve springs. I was pulling 7800 RPM shifts using 273 rockers. I never broke a rocker. (bent many pushrods though)
The only suggestion I have, is to not use the factory style adjusters,(they come loose too easily) Get a good set of lockable adjusters.