I have 2 cams for big blocks. One is a Comp High Energy 268 duration, .485 lift. The other is a Comp Extreme 4x4 262/270 duration, .505/.515 lift The two motors are: 454 bored .020 over, 781 casting oval port open chamber heads, in an '82 Stepside running 4.10 gears Detroits front and rear, and a 4spd... to be driven on the street as well as off road with 35" tires and occasionally 39.5's. This 454 currently has a .485 lift but 290something or higher duration cam, with two lobes going flat... so the valve springs should handle the 268 High Energy cam. 402 all standard as far as I know right now, out of a motorhome, open chamber oval port heads, that will be going into a '76 K5, 4spd, 4.56 gears, locked front and rear, on 38's, off-road only, never to see pavement, trails and mud only. What cam would you match with what motor?