Hi Kristian,
An interesting, if unusual design and a nice piece of CAD work and animation as well. There is an interesting model here showing how only one sheave (eccentric) and valve can operate a simple single engine which is similar to your proposed design. Worth a look, especially as it is made of wood and runs on compressed air. Perhaps a good and quick way to prototype your design before committing to metals n’est pas?
The simpler design is also perhaps a more efficient use of materials which is even more important in these days of environmental concern, aside from the financial costs.
Regards and good luck,
Terry