Your light on final gear IMHO for a 400, that's likely a big contributor to weak low end performance with larger cam causing heavy load leading to knocking. Realize those are RAIV heads on serious steroids, RAIV used 1.65 rockers and 4.10 (minimum) rear gear. A well selected roller cam setup could really make good use of those heads.
It's all good, time will tell, if it does what you want well, enjoy it.Looks like a nice ride!
