Okay, I found the typing error I was making. I used make info but
neglected to use make install-info. So info was being made but not
installed. As soon as I used make install-info, and then ran info org
came up as version 7.5 on an info org command. I've done a few makes
already before I ever knew what org-mode was but this was the first one in
which once info documentation had been created the make install step
didn't automatically install it. One might do this in order to check
md5sum on a file before it was promoted to system-wide status or do things
with private versions but I can't think of other good reasons for this
build method.