Help spec'ing out a new small block

If you stayed small block... I'd go r3/w8 or r5 p7 and just do a rebuild. It's easy to get 800HP plus. They're engineered to go LAPS at higher rpm. That's probably Mike Grey's old 417" "NOS" motor you saw listed. It was a good piece when he sold but I'm not sure if anything happened after it sold. That's probably a good fit for what you want to do and you won't have to tell the engine it's not going to be sprayed! Although you're probably changing from your initial post goals, it's very common to want to go 8's when you're so close. Now is the time to decide the bones/foundation because you'll hurt parts around a stock foundation at that level NA.