Rebuilt Engine vs. Custom Engine

I'm looking at buying a mustang and putting a 400CI+ engine in it. I'm trying to get an idea of what it will cost to do all the things I want, but am kinda stumped here.

Are there any major differences between buying a rebuilt engine vs a custom engine? Is the rebuilt engine alot less reliable? I'm assuming this is the case or else there wouldn't be a 300- 400% price difference between the two.

Any help I can get on this matter would be much appreciated.

wait for the ford racing 5L "cammer crate engine".
It will be very powerfull and reasonably priced.
should eb out soon.
do a google for more info.

Thanks, I will look in to it.

Would still like to know the major differences between the two.

Is a matter of usage more than source.

Many performance tuners like an iron block to have been thermal cycled to provide a more seasoned surface.

Many manufactures will also store the engine castings and allow them to rust before machining to get the same molecular alignment as a used block.

The builder and the tolerances he uses, and the parts he installs are the real deal.

You can get a dang good engine from both, but if used beyound the design it is junk looking for a place to happen.

Here is a dang good Stang Dyno run.

http://www.kcrealtime.com/images/John_Dyno.bmp