Sounds like a very solid build to me. You can reduce bob weight with the 4.25 x 2.2 chev big end crank journal, but if you already have the 4.15 stroke crank it wouldn't be worth switching. Should make gobs of torque peaking below 5000 for sure. My WAG is 725 hp on pump gas, enough to put you solidly in the nines with some bite. I really like the aluminum block for a streeter, we fight to get all the weight we can off the front and you are starting with a motor lighter than a small block. Still, anything you can do to mount the motor as far back as you can will help. You might only get an inch or so, but it is worth the effort.