There's several different engines you can make that kind of HP with, but your going to need a really stout engine. I would recommend maybe a stroked 351 windsor with a good sized turbo kit, but their are several engine that could be made to produce those numbers.
Try these company for a really strong engine. I would recommend calling them, and telling them what you want to do with your car, and they will be able to advice you better than me.
CHP short block long blocks engines crate motors
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Try here for a good Automatic trans.
Someone else on here can probably advice you on most of this stuff better than I can.