Your AC wire runs won't have a problem with voltage drop in a bus so transfer switch to breaker box distance isn't an issue. The DC wiring does experience voltage drop over bus length runs so check the link below for the correct wire size for the load and the length of the run.
In particular, your inverter should be as close to the battery bank as possible with a nice fat cable. It never hurts to oversize your DC wires but undersizing them can result in the release of the Magic Black Smoke, and possibly some phoning and fleeing.
https://www.engineeringtoolbox.com/a...uge-d_730.html