Indy heads single water crossover /single plane manifold.

Mine wasn't luck....it's called having a proper overall system on a car with the quality of parts needed for the job.......to be honest I really can't think of many issues at all that I have encountered so i'm either the luckiest builder out there or just spend what's necessary to have a trouble free hot rod.
Much like yourself I take great pride with my cars, never did settle for cheap or "ok" components especially engine pieces and the cooling system design. Just never got the same performance out of electric fans.
One difference maybe that I do run A/C, you know what it is like here in MO during the summer.