In the market for a kit

[dallas_]

Since you are 6' 4", you will find most makes to be a very tight fit for you.
I'm 6'1" and am tempted to modify the pedal box to add a little leg room.

Next time you are in the states, look up the local Cobra club and attend their next meeting. You really need to sit in some of these cars before you decide which make.

[PDUB]

The Unique 289 car will fit you, and it will fit better with your planned small block engine build than the 427 body style... check out these threads and click the embedded links for photos.

Unique Cobra For Sale

I'm to Big any advice

Good luck!