Here's the breakdown from Chevy Master Parts Books for your missing pieces:
GM Parts Group/Description/Part#/Qty
5.149 - Lever parking brake shoe 9-3/4" OL - Left GM# 596973 - 1 each
5.149 - Lever parking brake shoe 9-3/4" OL - Right GM# 596974 - 1 each
5.150 - Extension-strut, parking brake shoe lever 7-11/16" OL - Left GM# 597239 - 1 each
5.150 - Extension-strut, parking brake shoe lever 7-11/16" OL - Right GM# 597240 - 1 each
5.151 - Spring, parking brake shoe lever extension 19/32" ID x 1-7/16" OL - GM# 597241 - 2 each
5.158 - Bolt, hex head 7/16" - 20 x 1-1/8" w/eccentric - GM# 597238 - 2 each
8.917 - Nut, hex head 7/16" x 20 - GM# 121728 - 2 each
8.932 - Lock washer, internal tooth 7/16" - GM# 131718 - 2 each
Plus the 2 clevis ends for the cable to lever connection which have no GM# and must be sourced from donor vehicles as reproductions are currently out of stock everywhere.
As mentioned above, these are all found on 1937-52 Chevrolet and GMC 1 Ton trucks equipped with the rear axle parking brake mechanisms (not trucks with the transmission mounted parking brake assembly).
Just my best suggestion, but if you can't find a local donor truck, put an ad up in our Swap Meet
Truck Parts Wanted forum to see if any other Bolters can help you out. Note: A quick and easy way to post what you need in an ad is to just copy and past the info I've provided here.
Best of luck!
