I've got a new Goodwrench 350, mild Crane cam, Performer intake, Q-jet in my '75 Camaro. With the old stock motor I always ran AC R45TSX plugs with .060" gap (stock specs) and never had a problem, always ran strong. I'm still using the original stock HEI ,which has never let me down, on the new motor and am running AC R44TX plugs, also at .060 gap. This motor runs like a champ, healthy and strong. GM only used the .060" gap in '75 for emissions and then went to .045" gaps for HEI's after '76. Here's the question: I've always thought that the bigger the spark gap the more power; is it possible I could get even better performance if I switch to the smaller .045" gap?

I normally gap them all at .045 now for HEI systems. This is recommended in several plug catalogs.
I don't think the system will have problems with the larger gap, as long as all the components are working correctly, unless the engine is taken to the upper RPM limits of the distributor. The system may not be able to achieve the necessary coil saturation to give a good spark event and you could develope a high RPM missfire.
I would imagine you could see any issues by just spiining the car up on a dyno and watching the scope for spark event problems if your really concerned about it.

The HY ciruit has 2 gaps the plug and the rotor to terminal gap...it is the Total of these that is important...
Spark gap specs assume that the rotor and terminal pins are also in good condition...
As the total gap increses the resistance accross the gaps increases...the current will follow the path of least resistance
Larger the gap the more likely hood of leakage and crossfire from the HT leads, boots...these have to be in top condition.
Thu if these are in good condition oits not a problem