fouled plugs

So i finnaly had a chance to diagnose the old girl. From the leak down test i am getting oil past the rings. Looking at doing the rebuild i have come to the conclusion that i will be building another short block instead of doing this one.

Question to you all is i have spoken to a engine builder and he quoted to build me a 400 zero decked with the following
Machine work; bore/hone, square deck, align bore, resize and shot pen rods, kb-240 pistons, moparperformance 7qt pan, meling hv oil pump, an ATI dampner and solid flat cam (specs up for debate) for 4k. Does this seem reasonable?
He is also telling me with my current heads (906 stage 1 port, standard valves) and a .550ish lift cam i can look at 500+ HP and torque. Is he blowing smoke up my @ss?
I am undecided on whether to do this or a 451 Stroker from Musclemotors. cost wise is within $700 of each other. This is my daily driver, and i would like to run low 12s in street trim and slicks.

What do you all think?