Irrespective of the springs used, I suggest you read post #39 AGAIN.
Then, go to the i'net & read about alllllllllllllllllllllll the flat tappet cam failures, many from experienced engine builders with years of experience....
Without doubt and as long as we also keep in mind that excessive spring pressures during run in and poor engine building practises were killing lobes way back then (25+ years ago) as well!