It's uncanny to me how similar you 408 sounds to mine, I'll try to post a video of mine. Builds are fairly similar, IIRC your cam is .292 .501" lift? Mine is .236 .574" lift so that seems to be the only major difference to me outside of the carbs, you have 800 I have 950cfm. Both low 10:1 compression, both TTI, both Edbr heads. My biggest interest to your build relative to your numbers is did you go solid lifters or hyd lifters? You spun a few hundred more RPM out of yours getting you to 500hp/ftlbs, I fell just short at 489 each and spun to only 6000 on the engine dyno. Dyno guy and engine builder both agree I would most likely get another 300-500rpm out of solid lifters.