I've done it with the aftermarket heat only panel you are referring to.
acdelete.com manufacturers the panels others are selling. I got mine right from them, they were great to deal with.
It does require quite a bit of custom fab work so read thru the instructions and make sure you'd be able to do it. Nothing spectacular is needed but some guys skills are more than others.
Instead of drilling a bunch of cowl breathe holes in the top of the panel, I got an extra door jam vent and cut that in. Much better, stock appearance.
The panel frees up tons of room on passenger side too. Changing #6 plug is as easy as any of them.
In my signature has a link to my frame off thread. Pretty sure I put pics in there too of the panel, which I dipped in carbon fiber.
I'd be happy to answer any questions you have.