Why do I keep breaking rocker arms?

Specs have been hard to track down, as the rebuild was subbed out to a supposed 'slant expert' in Texas (don't have the name). Texas built the engine with a 'performance' cam of unknown nature and I'm pretty sure everything else is stock.

I'll add pushrods to my 'more info needed' list.

#2 and #5 valve adjusters appear taller because those two valves are lower, which seems odd as one is intake and one is exhaust. I realize that this is a dumb question, but are the valves all supposed to be at the same height?
Yes. The valve stems should all be the same height with the rocker shafts removed. What does the cam sound like? Can you distinguish it from a stock idle?