Just checking the obvious... The Sugino Messenger is a single speed crank and can only handle one chainring. You're intending to build a bike with a single front chain ring, right?
If so, using the Sugino Messenger with a 103mm BB will give you a 45 mm chainline (apparently, according to some Googling).
Sheldon Brown's article on chainline says that triple MTB chainline should ideally be 47.5 mm (i.e. the middle chainring is 47.5 mm outboard from the centre of the seat tube). So to achieve that you'll need to add 2.5 mm on each side, meaning +5 mm to the BB length... 103 + 5 = 108 mm BB
So don't choose the longest BB because I think, for Shimano UNxx, that's actually 122 mm ish. Way too long.
Just another note... That crank was originally intended for 1/8" thickness chainrings but you'll need to put a 3/32" ring on there for use with gears. Just in case you were about to buy another Sugino ring.
Of course, if you want more than one chainring up front then best procedure is to sell this crankset and buy a double/triple chainset/crankset.