the E with a thunderjett is a very tunable and powerfull upgrade and can run very nice, flows way more air. the other option that might work well for you is the Mikuni 42.
the G has so much airflow, that if you don't have the right compression and headflow work donne, it can acutally SLOW down the airflow and decrease low rpm performance, which to me is a no no. if you had enogh compression and airflow the mikuni 45 is also a thought.
m

 

 

what planet are you from?
a G or a 45 Mik on a 76'' sporty?
really????????????

 

The give away here is when ANYONE states "my mechanic says " -
You now have become Tarzan of the opinions as you swing from the vine of each one, never learning on your own.
Most of us that perhaps, might ,maybe know something, - know by actually trying this or that.
Even so, my circumstances might be completely different then what your objective is.
You would have to write a liturgy of defined objectives for someone to actually pick a carb for you.
TT run?
A wanabee red light racer?
Week end ET worrior>?
Cruiser?
There is no one song for everyone.

 

Funny thing is you can put anything on anything..... It's your dime....

The truth is you need to know what your heads flow. Up to 260 cfm, the E will work great. Once you start to flow more than 270 cfm then I would switch to a G...