Hey AmericanPie,
I really do like my 514! It has a C6 / 2.88 Powerlok behind it and can spin the back tires any time you wish. It has been "detuned" with a dual plane manifold and a hydraulic roller cam to reduce maintenance. I have 3600 miles on it since mid-June, including a half-hour's worth of laps at Summit Point yesterday - what a blast!
I'd get one built, though. I bought a Ford crate 514, and now have more money in it than I would have spent on a custom-built unit - Ford sent it to me with bad rods and a defective distributor and so far hasn't done much to ease the pain of some expensive failures...
The sound is great. It pulls well into the triple-digit speed range in a blink.
The above kit suggestions are correct - if you're gonna do this engine, you need to make sure the kit's body/frame allows it to fit. Some of the current kits that can use the 460 include the Everett-Morrison (defunct but now being made by CSC ->
http://glasssnake50313.tripod.com/), SPF, Factory Five and West Coast. There may be others.
HTH,
Tom