273 build ?????

The E-4 has a pretty flat torque curve. It's an old school cam but it works.
The 273 can't handle much of a cam because of it's small size. The more the cubes the bigger cam you can run. A 268/485 cam in a 273 would be big. I put one in my 454 in my tool truck and it sounded like a stocker. toolman