Barney played a standard length (19 fret) tenor banjo until quite recently. Since suffering a stroke he has now switched to a short scale tenor banjo (17 fret) to make life easier. He never played a plectrum banjo (22 fret) to my knowledge, the scale length of a plectrum banjo makes playing fiddle music too much of a stretch. Barney uses mandolin fingering using mainly the first three fingers to cover the frets, many Irish style tenor banjo players use all four fingers. He has always employed a plectrum (currently a Jim Dunlop 60mm nylon pick) in his banjo playing, not a thimble as popularised by Tony 'Sully' Sullivan.
The Music Room and Eagle Music both stock heavy guage Irish Tenor banjo strings suitable for short neck tenors.