The driven element is adjusted by using 468 divided by the frequency in MHz.
For example, 28.3 MHz equals 16.54 feet.  That old of an antenna probably
used a gamma match but it could be something different.  If it is, the
driven element will have an insulator keeping it from touching the boom and
dividing the driven element into half with any variety of tuning systems.
If it is a gamma matched antenna, even the driven element will be bolted
directly to the boom.  The directors are smaller by, I believe 4 percent so
the one on the very end will be much shorter than all the other elements.
The reflector, the element on the other end, will be the longest and is 5
percent longer than the driven element.  Spacing is based upon quarter wave
spacing from each other unless it is wide spacing.  With a 16 foot boom,
however, it won't be wide spaced elements but standard.  These are the
basics.  There are all types of variables based upon the type of antenna it
is.

Phil.
K0NX