It's never quite that simple unfortunately.
If we pulled the engine to add rods and pistons only.....you would figure maybe 8k or so installed?.. But...you need more...to reliably make this you will need more supporting items...
Keyed ati balancer...essential at that power lever
At a minimum fresh valve job...but for 900rwhp , id recommend fully ported heads...
You'll need a real fuel system with larger line, minimum of dual pumps..return style system with bigger injectors...
Clutch to hold the power. Centerforce is what id recommend.
And lastly a full exhaust, header back if you don't have it already
It just became far from simple...
But to simply pull the heads and set them On the bench...machine the block and install pistons..rods...new bearings, gaskets, and seals, youll end up around 8k give or take a few bucks. Heads un touched.