I think the normal stoker bull horns are around 46cm centre to centre. Certainly wide enough to clear a lot of captains but obviously not all. You will not have enough adjustment in that eccentric to take 2 links out of the timing chain. You will probably need a 130 or 140mm stem if you have a long torso/arms also. Ignore the seeing the front hub idea for setting it up. Put your saddle at the height and set back from the bottom bracket that you normally have and the set the distance to bars from saddle, and seat to handlebar drop from there.