Dean, first $400 seems to much for a Crown Graphic, secondly a 135 f4.7 Xenar only just vcovers 5x4 and is a touch wide-angle for a standard although quite usable stopped down well, no room for movements.

A 150mm is a standard lens on 5x4 but a 180mm or even 210mm are excellent for close portraits. The 135mm would be fine for more environmental portraits.

Barrel lenses are just lenses without an intregal shutter, you can get some great old portrait lenses at prices from a few $ or 's through to many thousands for some real cult lenes, but there's plenty of bargains around. Look up Petzval & Darlot, these are sought bafter in the US by some wet plate workers.

For many years some lenes were available in a variety of mounts or a shutter, so there's normal barrels, sunken mounts and sometimes a choice of shutter.

Ian