This is the latch I used, they can be found used on '85-'92 VW Jettas, Golfs and other models. It is set up for a cable release FWIW.
http://www.yogisinc.com/index.cfm/pa...d/prd13796.htm
Keep in mind that the filler between the radiator and the grille is different on a '56 and '58 so installing one might be a little different. I cut out the oval shape in the filler panel and welded in the lower latch from underneath. The upper latch was bolted to the existing under hood latch plate, only minor shimming and trimming was necessary.
Sorry no other pics and with the truck blown apart I cant go take one for you.