First off what are your plans for the car? Street, strip, road course/ autocross. All these will stress the engine differently. Also I see that your looking to make 700-800 rear wheel hp. That's going to require a lot more work than 700 flywheel hp.
If its an early '99 model then you might have the Teksid block which can be built to hold 1000hp. If its a WAP block they have held 1000hp built right but 800hp is safer. I'm not certain on the iron blocks but I believe they are good for 1000hp as well.
One of the main areas to pay attention to on the WAP block is the window openings in the crank area. You'll want to radius any sharp edges to relieve stress risers. Also take it to a reputable machine shop that has done mod motors before. If your building it yourself do lots of research as to what all is involved. If someone else is building it make sure they have experience with the modular motors as well.