This...
and this...
have also caught my eye
Unfortunately, as mentioned, by the time you've paid all the required charges (25% of your purchase price and shipping cost on top), the reality is that it's usually cheaper and easier to buy something here unless you're looking at something very rare, or special.
Let's put some perspective on it. That Mach 1 is $4,550, and lets say it's going to cost $1,500 to ship it. That's $6,050 - £3,752. So once it's landed here and cleared customs, it'll stand you £4,690 for a completely unknown car that's got 140,000 miles and has had a cheap blowover - so God knows what's underneath. You'll easily sink a grand or two into it in parts, then it's on to the metalwork......So you're up to about £7,000 already and it's still not ready to roll by any stretch.
In the UK you can buy an utterly utterly mint '71 Mach 1 (admittedly slightly different styling), with about 64,000 miles, for £10k. That's a car you could physically see, test drive, and not have to do anything with to be able to enjoy it.
Many a time have I looked at buying another Corvette from the States but because of the import charges (plus the grief of getting it registered correctly and buying something unseen) it actually works out more expensive to buy it and import it, instead of just buying one here.
Plenty of decent projects in the UK if you dig around - for example I watched a complete rolling early 70s Ford Mustang Mach 1 go for £2,000. Do be careful though - the trim, weather seals and detail bits (which are what's usually missing) can add a small fortune to the price of any project. These things rust too, as most of them haven't been cared for, so dig around carefully.
Get a copy of Custom Car, American Car World and Classic Car Weekly from Smiths, look on Rods and Sods, the NSRA forum, Mustang Owners Club, Pontiac Owners Club, Mopar Muscle Association UK, and so on, to get a grip with what's available at certain price ranges.
For my money I'd be poking around (as much as I dislike them) 80s Camaros - because at that money you'd stand to get a running and driving one that can be improved with great ease, as opposed to a rotten nail that simply becomes a moneypit that you never get to enjoy. Either that or a Fox-body Mustang, but those are quite thin on the ground.
The more period and less well-known models from the likes of AMC, Buick, Oldsmobile, Chrysler and so forth can sometimes be found quite cheaply, however, but you've got to have your head in the game to spot them and dig 'em out.