Have you modified the mufflers???
By drilling acouple of 10mm holes in each baffle you can add a few hundred RPM.
By installing a battery ign you will save about 9-10 oz. Its mostly spring starter weight. Also maybe a few RPM more because no clutch drag from the spring starter.
On some GT 74 with the CH ignition there is a 1-200 rpm gain, on some 0 rpm gain. Lots of variables and we don't know why.