There are 4 blocks in the BII for the pipeline truck (in addition to the standard block used on all front winch equipped trucks). From left to right you've got the block with welded hooks for the rear anchor, the block without hooks for the center anchor, the block with the trunnion, a block with a hook pinned on, and the front winch block.
You've already got the anchors so that's a good start. The book lists a different part number for each block because the anchor/ trunnion went with the block when you ordered them. They're all the same except for the one with the welded hooks and those are easy to weld on.
The NSN for the block with the pinned on hook is 3940-00-151-6769. The military still has these blocks kicking around and they were on ebay for a while for around $200 each. When we were putting together the rigging for our truck we won a lot of 8 blocks from GL for a bit less per block. The attachments just pin on so remove the hooks from 3 and keep one with the hook.
After that you'll need to cut out a couple pieces of 1/4" steel in the correct shape and weld them to the sides of the block for the rear anchor. Very easy to do. The block in red primer is my homemade rear anchor block next to a friend of mine's original block.
For boom chains we're using 3/4" pear links to go around the trunnion. Not an exact match but finding original boom chains will be next to impossible. The chains are 1/2" and just under 24 feet long if I remember right. Get a 50 foot length and cut it down. We're connecting the pear links with some small shackles and then the other end of the chain needs a grab hook.
If you've got any questions about individual pieces or anything in the BII list just let me know. I think I've got it mostly figured out at this point.