Brian,
The 1969 Body Assembly manual page is missing for that detail, so assuming that Ford did not redesign everything for every year, using the 1970 Body Assembly manual, which uses all 69 part numbers for brackets and braces (the valence is a 1970 p/n), the bolts should be the same as the other end of the fender brace, and use a nut clip (2 bolts, 2 nut clips per side per car that brace). Hardware specifics are: bolt, 57060-S2 1/4-20X5/8 thread length plus a lead point, disc washer; nut clip, 45263-S2 1/4-20 0.960 L, 0.610 W. Both items are available from AMK but the bolt is -S36.
Jim