D28 string gauge for low tunings

[dan!]

I'm playing around with this excellent Led Zeppelin song: https://youtu.be/q293yljkU0o

I usually set up my D28 for fairly low action in standard tuning using 12s, so this Open F (CFCFAC) tuning is crazy low tension using the same set of 12s. Lots of buzzing...though the guitar sounds fabulous this low...

So, two questions:

What gauge would folks with more experience in low tunings use? 13s? Even thicker? Or maybe shim the nut up higher and keep 12s (which are super pliable and electric feeling when tuned so low)?

What other songs should I look at it that use this tuning? I'd love a few tasty pieces to go after if I'm going to adjust my setup to play well at this tension.

Hugs!
Dan

[Mike McLenison]

With my Martin HD-35 I've set it up for 13-56 and tune down a whole step. Then. when I do drop D tuning my low E string is a C. Still is loud and clear. No fret buzz anywhere.