Bob,
    I haven't tried actually changing anything about the engine plumbing on
my cessna cutlass which has a Lycoming 0-360.
It has really horrible fuel distribution ROP but as you get close to peak
suddenly everything flattens out.  You can slightly help this by adding a
little carb heat.   I haven't succeeded in actually getting more than 15 dF
LOP but if I'm above 5000 (or below 21" MAP) I'll run basically at peak with
good results.

Colyn