First of all, any Cobra owner is more than likely to tell you that you need to buy the same brand Cobra he/she has purchased. That's just human nature.
By the way, you need to buy an ERA.
That out of the way, I see your budget is $35k. I'd say that pretty much pushes the big block or small block question over to small block, as those FE's are mighty expensive to buy and maintain.
Many Cobras when built from a kit quickly rack up to be about a $50k investment. I recommend looking at the used market for a Contemporary or a Factory Five Racing Cobra with a small block and a 5-speed (I'm thinking you'd want to squeeze out as many miles as possible out of that litre of petrol over there). There are a LOT of FFR Cobras on the used market. Sometimes you can pick up a kit that someone had started but never finished and get a good deal.
Take a look at
427 Cobra Country--Ford AC Cobra replica manufacturers SUPER-SITE and see if there is anything to your liking. Check on the cost of shipping overseas. I've known of guys that have purchased Cobras sight unseen and have had help from the Club Cobra crew getting the car picked up and shipped. You've found the right place.
Dangerous Doug