Joined: Jul 2015
Posts: 7,159
Likes: 3,104
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
go get some bolts at the bike shop. or order some... those crank bolts are of a universal design... serrated flanged head... there are Allen head design, or 14mm hex head design... the Allen style have a black plastic piece included that fills the space normally covered by the covers for the hex head style... either will work fine....
as to the crank arms being trashed... half a block won't do that, but you MAY find that the previous owner went too far...
and CLEAN everything before reassembly.... then look the tapers over real close... report what you find.
get the bolts, torque them properly, and go ride again.... keep an eye on the snugness of the arms to the spindle, though... check them at every chance for a couple rides, and then every pre-ride inspection, ok?