Simple and elegant, the first gen Carrera. Although a lot of model variants exist, so there's often the temptation to add another... then one more... Perhaps I'm just weak-willed :)

The crown on the 7753 is usually signed and I've seen them between 6.4 and 6.7mm - the key thing is more the width, Carrera crowns are notably thin compared to many other Heuer crowns and it looks unbalanced with a thick crown. And I'd be wary of using the stop/start pusher, that cap looks about ready to fall off!

Just having the 1/5 second bezel in will make a big difference to the looks - I think people see some lines missing or it ages more than the dial and have it removed, but the Carrera just looks off without it, it's a key element in the design.

And finally, welcome to posting - lurking is fine but posting is more fun :)