While I do agree that the 400 is underappreciated, it isn't the most modification friendly. No race style intake manifolds, and the 429/460 style bellhousing pattern isn't friendly in the swap department. And just how many people are building race engines out of derelict 400s? I have just one answer... None. The fact is there are more people building and modifying Y-blocks than tall-deck Clevelands. I might even venture to say that the tall Clevelands are right down there with the MEL (383, 410, 430, 462) as far as sought after engines for the automotive hobby. Maybe not a bastard, but definitely an orphan.
That aside... the 400 has always had incredible potential. I used to tell my brand X friends in shop class in the early 80's about building a bad ass 400 and they all thought I was insane. The fact that Jon Kaase took a junk yard 400 and made a 4-time Engine Masters Challenge winner (...with the very same engine) is not only testament to his engine building prowess, he knew and was able to unlock its hidden potential.
All this does for me is fuel dreams of a mid 70's Torino or Montego with a rippin' 400. What a sleeper it would be!