In the US a small block Chevy is the most common and easy answer. That's a 265/283/302/307/327/350/400 made starting in 1955 and still available from GM.
Most V-8 powered Chevrolet's will have one of these motors. If not, they have a newer similar, but different motor, or they have the big block Chevy motor, which is a 396/402/427/454. My knowledge of the newer motors is limited to knowing the exist.
I assume you want to go with a car type 4-speed or 5-speed and not the truck type with a granny-gear first. You'll probably be best off buying front and rear crossmembers instead of trying to use the stock bellhousing mount.
A Camaro is likely to be a good source of the motor and trans you want, but not the only possible source.
Since you are in Europe I'd be tempted to consider some other motors. The Rover V-8 is based on a motor first built by General Motors for use in mid-size cars. They aren't hard to find around here, but might be easier to find than a Chevy in your corner of the world. Not as big as the typical Chevy, but in a small pickup should be capable of great performance.
