Your Gibson is primarily an acoustic, especially if it's the Gibson version of the J-160E.
Note that the whole issue of Pyramids is kind of a sticky wicket

in Rick circles...truth be told, both metallurgy and core gauge have changed since the 1960s; the result is that the sound will be different from vintage. I have a '67 625 strung with vintage Pyramids and the feel and sound is quite different from what Pyramid is selling these days.
A short-scale Rick is not known for sustain. Flatwounds will further cut whatever sustain it has. I don't have tension figures handy for the .013 flat Pyramids, but if they are like the rest of their guitar line, they will be higher tension than the Rick round wounds.
These are things to consider.
You might want to consider the T-I Jazz Flats in the heavier gauge, too.