They aren't that tough to make or to have made up. The Valve covers are on ebay on a regular basis. I used 1-1/4" steel tubing & cut them at 11.25 angle to make a 22.5 angle for each cover. the bottom tube I cut at 2" & the top at 4". The gussets I made from 1/16" steel & used paper the get the shapes correct before transfering the templates to the steel. The Sources for the breathers & decals I listed above.
BTW, I have changed my user name to try to resolve some login issues I have been having with my Tongue Pirate account. If this doesn't fix it then I'll know it's just me