I ran some clear 3/16ths fuel line and a small universal fuel filter from the parts store with 1/4" fittings. The fuel line was a little tight going on the filter, but it works and seals well. The main thing to look out for is that the fuel filter isn't too long, because the run of fuel line from the tank to the carb isn't very long and requires 90 degree bends. Most small engine/lawnmower type filters will work well though, either 3/16ths or 1/4.
EDIT: If I had to do it again, and probably for next season, I would run a filter more like this one as it suits the space available better than a more tranditional "canister" style filter.
https://www.amazon.com/Visu-Filter-U.../dp/B00J4ZAQP6