cam duration

I think 216 could work in a teener. I'm pretty sure I could make it work. I'd like to see closed chamber heads, a tight quench, and one of the following cams;a 256/114, or 262/112, or 268/110 cam. This makes a Dcr of about 7.8 and cylinder pressure around 153. Total chamber volume around 77 cc. Allowing 14 for the gasket and eyebrows, that would need 64.5 to 65 cc in the heads.
All these cams can be installed at a 58 to 60 degree ICA, and would not affect the Dcr to any degree,varying cylinder pressures about 3 psi
Choose the cam according to useage.
If you're stuck with open chamber heads, getting 9.5 is tough.
If you have an engine other than a teener, nothing above applys