I am installing a 50 amp power inlet box to backfeed my 12000W generator (it has 50amp outlet) into the house main circuit panel (with approved interlock kit..). The inlet box is a GE T050N, that only has punch outs on the bottom, and bottom of sides. https://images.homedepot-static.com/catalog/pdfImages/b5/b535b44c-bc9b-47b8-ae55-7859edf6623d.pdf
See my installation zone in the picture below. I was thinking of putting the inlet box directly below the main panel and run 3/4" PVC conduit down from the main panel and into the lower right side of the inlet box. I've been looking on the web for rules on proximity of the natural gas meter regulator to electrical boxes and couldnt find a consensus. I live in Texas and local municipality has adopted 2018 version of Building code, NEC, etc. Any issues with the proposed location? from what I've read on wire size, I need to use 6/3 UF or #8 THHN in the conduit, sound right?