I also got the stock complete.
The screws for the cap are supposed to be 6mm. I used 1-1/4" long #14 screws. The top one is supposed to be a button head and the bottom an oval head. I searched, but couldn't find any with slotted heads.
For the top I used a pan head. After the galvanizing was stripped I filled in the phillips head with weld. While spinning it in a lathe I used a file to reshape the head. A fine tooth sawzall blade was used to cut the slot. I did the same for the bottom screw, but started with an oval head.
The holes in the cap needed to be enlarged. The bottom hole was also slightly countersunk. The pilot holes in the stock were enlarged. With wax on the threads the screws were installed.