Valve Cover for 1981-1987 Hydraulic Slant 6

Looks like you found one. I had that same issue before I ended up swapping the slant for a small block. I was told you can swap the head for an earlier head and keep the hydraulic lifters and rocker arms etc. That way use an earlier valve cover, which is MUCH easier to find. If I remember correctly it had to be a pre-'72 head to fit the lifters through.