leaking holley 3310. hard restart

Was it installed correctly?

Could also be a percolation problem being that it mostly seen when the engine is hot (although i have never had a heat related issue with a Holley in my 25+ years of running them) but it's weird that this is manifesting itself at the transfer slots.

You could try a thicker carb to intake gasket.

But I still suspect an internal leak (improper gasket or installation, and/or PV) as the most likely cause.