Old bows like that indeed are popular for bowfishing, since they are inexpensive and bowfishing can be rather tough on them. Metal cables with Dacron strings........pretty tough, but if the cables go you might as well dump it and get another.
The cost of a recable would be at least $60.........if somebody has new old stock or the old stuff to make new ones (there is a place in CA IIRC that makes cables for old bows, some having proprietary swages on the end).
If it checks good, shoot 'er til she blows (which may not happen for many years). Old bows, ya just never know. Heck, some new ones let go due to defects.
Currently shoot a recurve made in the early 80's and have bowfished with older recurves and compounds.