Guest Al made a good point; did you build the neck with 3 extra frets like the Vega "Seeger" banjos? If so, tune it to eBEG#B.
One of the oddities of long neck banjos is the fifth string tuning peg. On the vega long neck, it's located at the 8th fret (as opposed to the 5th fret) and you have to tune the fifth string up a step and a half from "E" to "G" when you capo the 3rd fret for standard G tuning. You then use your "spikes" as if you were using a standard size neck.
I don't like tuning my fifth string a step and a half every time I capo (the change in string tension causes the other strings to go out of tune) so I came up with an alternative:
I use a heavier gauge string on the fifth string and tune it to E. I then tune it up a half step for the key of F (capo on fret one). I leave the fifth string up a half step and spike the 10th fret for the key of G, the 12th fret for the key of A, and the 14th fret for the key of B.
This seems to work better for me as I switch often between open E and the capoed keys.