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