if they are the aluminum roller rockers..

i bracket raced for 2 years with a set of the 1.5 aluminum roller rocker on a 340 with a mp 557 cam.
I did not have any problems with them.

basically a 6500 rpm and shift bracket engine...

Tony

70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)