I probably have a unique perspective on this as I was in your daughter's position about 15 years ago. My Dad and I bought a 68 GTO HT for $700 and rebuilt it.
I won't insult your daughter by advising you to limit the power down. If you judge she's mature enough to handle it, then great.
For the short block I would concur with everyone else with one possible exception. I'd get new rods, and pistons. I probably wouldn't bother with forged pistons. They're more expensive than cast and not as thermally efficient as hyper-eutectic (modern cast) pistons and are somewhat heavier. All of which leads to they will give you less hp than the same setup with cast. Cast pistons are good up to about 1.3 hp/cu inch, which comes out to about 500 hp for a 400. I doubt if you're going to shoot for that kind of hp for your daughter. To improve octane tolerance and cooling I would zero-deck the block.
On the top side I would probably put the 16's off to the side and find some newer heads which will give you a more reasonable compression ratio and will already have hardened seats, and a few other nice features (like screw-in studs). If you're not a stickler for originality there is no reason to run the 16's. 4X's or 6X's off of a late model 400 should give you a reasonable CR with minimal trouble.
Keep the intake as the stock cast iron's are very good.
The carb oddly enough is an area that is hotly debated to almost a religious fervor. It boils down to preference. Square flange carbs (of any manufacture) are not as responsive and not as fuel-efficent as spread-bore carbs. Square flange typically produce better WOT (wide-open throttle) power. Holley's are easier to "tinker" with but have a reputation (earned or not, it has not been my experience) of being tempermental. Q-jets are a little more complicated for tuning (from what I've seen) but are excellent street carbs (spreadbore design). I run a spread-bore Holley and the current engine is very close to what you're probably going to build and I've gotten 26 mpg on the interstate going 70+ mph. I jetted down the primaries and jetted up the secondaries.
The cam is the heart of the engine, and everything else you do should work with it. I like Crower cams and I'd probably go with either a 60917 or a 60915. About any mild cam is going to work as the size of the engine is going to give you more power than about any other car she might encounter. Whatever you do, don't over-cam. Too big of a cam will lead to disappointment (been there, done that, got the t-shirt).
One thing I will say and I can't stress this enough, replace EVERYTHING. The only things I would reuse from the current engine are the block, the crank, and the head castings. I didn't when I built my first engine and I regretted it greatly later.
Bill
gearhead/computer geek (no the two are not mutually exclusive)
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