[afret]

Comp Cams recommends 10.5:1 compression for their 308R High Energy street roller which has 262* at .05 (176* at .200) and at least 11:1 for the 292XR which has 254* at .05 (176* at .200). I'm confused. Shouldn't you need more compression for the 308R since it has more seat to seat duration and less dynamic compression?

 

[rmcomprandy]

Cams for different engines altogether; from what I remember.

The only 308R which I know about is for an FE engine not a 385...with that being the case, the port flow characteristics are enough different to warrent needing a different compression ratio.
The valve lash is different for each lobe, too.
Otherwise...I don't know.