I'm still just a :baby: here but here is my advise...
If you want to have patience, build your block first, then run dual pumps and 100% over injectors, I would prolly still run exergy 10mm cp3's in this set up, with a 4094vgt and a 4788 over it and you would have a sweet set up,(you could go real big and do a 42/55 set up) or Borg equivilant would be just as good I suppose, but I like Garrett stuff. This set up should get you to 750whp with ease, massage the turbos a bit and 900whp should be possible, and I have been told runs cool enough to tow with 650whp
Or if you want, you could upgrade to the 4094 now and run 40% overs on a conservative tune and be ok, still , might/should need a moded cp3 to keep up with the injectors, this would put you well over 600whp. Not sure how long it would last(your pistons) depends on tune, and how you use it(as always, built or not) I have been told that dual pump on stock internals is a recipe for split pistons and bent rods, but do what you want
One of the Danville guys was runnin a vgt 72 a 10mm cp3 and iirc 40% injectors and he did fine for a year or more at your target goal of 685whp or close to it...
I wouldn't push your stock block to the brink unless you have the coin to build it the right way when it breaks, and another vehicle to drive in the down time, also, another thing to consider is the g-80 in the rear end, it's not gonna like all the added power, mine didn't, and it let me know by locking up and puking out chunks of metal, this was at 600whp and considerable abuse, add another $1200 for a Detroit truetrac and the labor to install it along with fluids. Just food for thought.