[dana]

Bluerooster,
There are many variations of big blocks: 427, 428, 429 are the basic ones.
Of course each one can be 'stroked' for larger displacement: 427 to a 454 is one, 429 can go to 460 or 514. If the block is bored out the numbers will be slightly higher.
Ford sells crate '429's' as either 460 or 514, they have 2 (or did 2 years ago) 460's with different setups for 485 or 535 horsepower. their 514's are rated at 600 horsepower.
From my research years ago, (just 2) about half of the original 427 s/c came with 427 and half with 428. The supply of 427's were scarce and cost twice the 428s, so...
The 427's were rated at 425 hp and the 428s at 350 with the same torque. (this is all from memory, and I have sometimers)
427's are going to cost between $ 12,000 and 25,000 to build. I have heard good things about southern automotive. I know 2 guys who love their 427's from them. My neighbor had his 427 built for $25,000, a little pricey i would say.

If you go ford crate, then some of the big blocks will be less expensive than the stroker small blocks! I got a 392 small block stroker for more than the 460, and the 514 was very close to the same price!

I drove both a small block and a big block back to back to back to see how they handled, how they accelerated, how the came out of turns under power. I was used to porsches with small hp and great handling, and high speed capiblities.
I could really feel the difference in front weight of the bb vs sb. I was looking for a driver not a show car. (I would rather drive to a show, walk around for half an hour, then drive for another hour, than I would to stand around for 3 hours talking about cars).
If you will be a car show guy, buff and shine, rather than drive, the 427 bb will way more impressive than saying it is a 351,392,408 stroker.

Of course if money is no object you can build an all aluminum block bb with alum heads etc and have the same weight, more hp and way more torque, for about $ 10,000 more. You can also spend big buck on a small block custom stroker and get fairly similar hp number, the torque will not be as great as a bb.

So, bluerooster, you need to decide what kind of cobra guy you are, how you will use it, how much you want to spend, etc.
Dana
Ps. This is the hardest part of the decision. Unless you do not care how much it costs, then it should be easy.