I'm pretty sure those are just regular old H6054 sealed beams. I just took a set out my car so they were handy to measure. I got the same measurements as you.I measured it 7.8"x5.5" (koito sealed beams), I think they actually go by 142mm x 200mm. I could only find 7"x6"s and 6"x4"s. WTF!
Can't find any
Further looking on the internets yeilded this link http://www.donsbulbs.com/cgi-bin/r/b.pl/1.15342078070206/h6054~usa.html
Yep, those are most likely H6054 sealed beams!
As a little aside, you can replace the sealed beam with a housing that fits perfectly. The housing takes replaceable/upgradeable H4 bulbs that will give you better illumination.