Seems I see in most accounting of 124 Twin Cam builds, through videos, posts and builder websites, the use of more heavy duty rocker support plates. Billet from Vulcan, Wood, Cycle Solutions - and forged SE from Harley.

Then specifically I read some builders recommending to use the stock rocker supports. My builder included, stated the stock pieces (supports and rocker arms) are just fine. As well, the use of stock over billet seems to be a more recent idea as posts/info from just a few years ago nearly always recommended billet support plates.

What I have not learned is why the stock pieces are sufficient. With the heavy duty parts, claims are reduction in flexing of the stock plates. Do the stock plates flex? Billet breathers are also said to be better. Again, I don't have a handle on why.

I might expect it would be good insurance to have heavy duty support plates, but then again could be overkill.