After testing as much basic items as possible, talking with the previous owner, and doing some math I have realized the problem is simply the wrong group of pieces to make the right package. The static compression ratio is 10.48:1, but the dynamic compression ratio is 8.9:1. Also the plugs are 2 levels too cold. The motor is a stroked 383 (4.030x3.75), decked to 0.020, .040 head gasket, 62cc TFS 195 heads ported to 66cc (liquid tested), flat top pistons with 5cc reliefs, 5.7" rods rolling a 225/241 @.050 .500/.497 107 LSA @ 110 ICL  comp cams Thumper variety rolling lifters and 1.5:1 rockers. I have a FAST EZ-EFI ver 1.0 which makes tuning the idle impossible. The 19 degrees of overlap offsets the O2 wideband which the corrupts the idle fuel table.  The EPA hates me (doesn't matter really) and I don't want a race car! 

     My conclusion is to drop the static CR by changing head gaskets to a  .060" variety and drop the dynamic by changing the cam for both an EFI compatible and with enough lift to flow those big heads. Howards cam 110245-14 having 225/231 dur @ 0.50 with lift 500/510 on a 114 LSA  on 110 ICL. This will have no overlap and a dynamic CR of 8.15. 

     This should have a slight lope at idle making good vacuum and pull strong through the midrange. All on pump gas, all day long. I would appreciate any insight anyone may have while I start sourcing parts. 

My LeMans CE Z16 at LeMans and the newest member of the family.  Both well above 400 HP and happy to run.