I picked up the factory assembly manual that is sold on Ebay but even though it is advertised as 47/54 it is a reproduction of the 54 manual. It does have lots of useful information in it though. I see that Classic parts has it for less than I paid for it Page 3 in the pfd catalog
http://www.classicparts.com/WebCat1_Single.pdf They also show the spring bolts for more and the shackles for less than the NAPA prices so a bit of shopping around may be prudent.
The "bolt" that goes through the spring eye isn't actually a bolt as it is more of a fitted pin that fits the brass bushing in the spring. The bolt/pin is drilled for a grease fitting to lube it and the bushing.
NAPA still shows the bolt and bushing kit
http://www.napaonline.com/MasterPage...d=7&SubCatId=3
That might give you a "keep the other guys honest" price.