There aren't any huge differences for someone needing a 4v motor so they can drive their car. The only large differences are different cams, possibly valve springs, and flywheel (meaning 6-bolt compared to 8-bolt crank) (and I have a flywheel for a Mark VIII engine). I could also sell you the engine OUT of my cobra, which has 60k miles on it, but that is going to be a nice bit more.
Here's my for sale ad, speaking you don't have the ability to PM yet.
im looking to buy a cobra motor mine has 186000 miles on it and it started ticking does anyone have one for sale in good condition