The shirt sold by Townsend is a good example, although I believe the collars were generally smaller, closer to a band type collar for the common man. A lot of reenactors make our own. It's a fairly simple procedure, the pattern is all rectangles.
I was there for the 60's as well. My memory may have been dimmed a bit by time, but I was never a big fan of "better living through chemistry". I'll 'fess up to having had a couple of the "Ghillie" style shirts in the closet. One was even velour, heaven help me.