Well, we just finished installing a couple all aluminum 572 CI / 750 HP monsters in 2 cars. A 67 Chevelle SS 396 and a 57 Chevy 2 door hardtop. The 572 causes a couple of extra problems over a normal standard deck motor due to deck height and stroke. The deck height causes the need for special headers, also raises the over all height of the engine. The stroke creates a big problem because it requires a 5" deep pan which caused us to have to notch both oil pans (Chevelle had to have tie rod notches made into the pan) and notch the frame crossmembers on each car. We had to run a 2" cowl hood on the Chevelle and had to make custom mushroom air cleaners for both cars to keep the motors under the hood.. So there is a lot more fabrication then say a 540CI motor.
Unless you have a shop and can do the fab work, I would recomend a World Class 540CI from Bill Mitchell. I use and sell a lot of these motors, and they make the power, and are priced well within your budget. And a 540 Bill Mitchell motor will stomp a mud hole in a GM 572.
You can see a few pics of the Chevelle and 57 over at GPSuperStore.com in the Prodigy Customs Projects section. The 57 is not 100% finished yet and did it's maiden voyage today. The 67 is kicking ass around town for a couple months now.
I will be adding a lot of pictures in the next few days. We did a bunch more then just motor installs on both cars.
http://www.gpsuperstore.com/forum/forumdisplay.php?f=15