Heron v1.5 was designed before the invention of TC, the use of fat wires and when the lung vaping wasn't known. You can widen the air slots and the air intake between the posts, but you may face new challenges.
Things as unbalanced wicking causing dry hits or/and leaking issues and perhaps the need for new posts with longer post screws or clamps. Of course, the chamber lid cannot be used with bigger coils.
Spheroid and Heron have restricted deck space on purpose and their ultimate performance is delivered with 2-2,5mm coils, 28-32 gauge and resistance value range from 0,5 to 2,1Ω.
Thanks for the comments old friend. I've always known by design that they were intended to be tootle puffer gear. And I well know about the issues when I re-engineer my vape gear, including trying to make them do what they were not intended to do. Some said the Chalice III's couldn't be made into a DLH atty, including Mark himself. Not true, I proved they can when I re-engineered one of my 6 of them.
As for the Heron as a dedicated lung hitter I only got by with them on the GP tube mods way back when I ran them by slip streaming the DT's. But flavor rich vapor suffers from doing so. In part why mine saw very little use those few months I ran the GP tube gear. I like the concept of the Heron though, so would use 1 or 2 of my 4 again if I could do unrestricted lung hits with them. Was just thinking out loud, and will ponder it more as time allows before doing anything with them. No hurry, they don't take up much space in my several large boxes of out of service gear.