[Y-Blockhead]

Welcome to The Barn TJ.

Edit: After re-reading your post, the following may not pertain. I thought you were asking about the carb leaking when sitting. Sounds like yours is leaking when running?? I left my incorrect response because it may help someone with the problem I described. Good luck...

I know this sounds off the wall but check the Tank Shut Off Valve for seepage. I have found that if it seeps just a little there is not enough head pressure to keep the float needle valve seated and the carb will dribble out the hole in the bottom of the throat.

With the Tank Shut Off Valve closed try disconnecting the gas line at the carb and put a pan under it to catch any gas. Empty the pan and place it again under the gas line and let it sit overnight. In the morning if it has a little gas in it, the Tank Shut Off Valve is seeping.

I fear this is one of the reasons you see people install a second valve in the gas line.

Good luck.