If you want to learn the triple stroke,split stroke and fan strokes
they will all work,whatever your tuning.A lot of Formby stuff was
played on differently tuned instruments,sometimes D tuning which
was common back then.But he also used C tuning as we do now!
Most Formby players use a Soprano Banjo Uke, as it is louder than a regular uke & the fretboard is smaller than any Concert sized ukes & is therefore easier to do the 'tapping' and 'reaching' on the Soprano, tho realistically, any uke can be used.