I think I'd make a possible correction,depending on state. Some states hold fast to the certificate of origin dating regardless of engine. My state did not hence titled as '66 because of engine.
Suggest the same as fixit on priorities. What you CAN do is begin going to Ford oriented swap meets and shows and learn about the 427 parts that are available. Cast iron blocks are still out there as are heads and manifolds. LeMans rods and steel OEM cranks are still around too. Start getting to know the "Ford guys" in your area.
If you're thinking 427 for real, it sounds like you're trying to make the car as original as possible. If that is true, I'd suggest looking at kit manufacturers who offer a round tube chassis built like the originals were. Several do this.
The best advice I can give you is don't buy a cheap kit. There's lots of cobra wannabe junk on the market just waiting for someone inexperienced to come along. They all look great in pictures, until you start looking at the shape of the car and it's dimensions.
Also, when looking at various kits, remember you don't have to buy the whole magilla. You can buy just the chassis and body and do your own sourcing for the correct hardware and accessories. Actually, that is a lot of fun and very educational.
I thought I was pretty well informed about Cobras, until I began to source the bits and pieces to make the car right.
The other aspect of this outsourcing method is that you can operate within your budget and still get the high quality you want to make the car right. Buy one thing this month and something else next month and so on. Yes it takes time, but hey, that's part of the fun of doing one of these cars.
Your first job, if you really want the car to be as much like a real Cobra as possible, is to spend lots of time around originals. Take pictures, ask questions and look at the little details.
Most of all, select vendors VERY carefully. There are sharks out there. Don't let a bad vendor experience spoil the fun of having your dream car. Brent Mills, the owner of this site, has had a lulu of an experience with a supposedly very highly rated engine builder.
Last but not least, have a ball. You're about to undertake the adventure of your life!
