1. dunno, yea you probably could get away with the GT40 heads....but you might like to try something that flows a little better especially if you're aiming for 700hp.

2. I have a friend that built a 5.4 that cost $30k+ (canadian funds) it's making just shy of 600hp at the wheels(2001 Lightning) Might be a little cheaper as you're not running a modular motor but then again, you're looking for 100 more hp than he's making. I dunno if it's the same this year as last but you were looking at around $1000 per tenth of a second last year.

3. The cheap way out I guess is your motor with a MASSIVE shot of spray.
I don't really think there's a cheap way to make 700+hp. If you want reliable power, you need a strong bottom end and a good set of heads. If you just want to make big hp a big shot of spray and lots of spare parts will do the job I guess, but that'll probably end up being more expensive in the long run.

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