Hydraulic roller Comp Cam 20-746-9 265/273 .506/.506 with a 1.6 rocker http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=661&sb=0
It's a fairly mild cam but the rule of thumb I've heard is every 25 CID is 5 degrees duration so a 265 in a 273 is a 275 in a 318, 282 in a 360, 292 in a 408.