I can't speak specifically about Gretsch Renown. But I've found the Ahead bags to work great on almost every drum that I've tried. The only exception so far being Mapex Orions. With the ITS suspension mounts for the floor tom legs, the brackets end up sitting pretty far away from the shell. The drum still fits in the bag, but it's a bit snug around the leg area. Every floor tom that I've tried with standard brackets bolted straight to the shell has fit just fine.
I just bought a new Gretsch Renown kit so this just prompted me to look into it because I'm also thinking about getting Ahead drum bags.
I'm confident they will fit. Most floor toms jut out about the same distance, give or take a half inch or so. Also, I've only read good things about the Ahead bags and haven't seen any complaints that drums do not fit.