Thom, you are probably right about the Griffiths.
i still have my old evaporator somewhere in my garage. let me have a look at it tonight, and see if i can find any marks on it, that can identify the manufacture.
this way or the other, the Griffiths is a recommended evaporator, that i know some people use on the air cooled Porsche's AC upgrades (was spending some time on the air cooled section on the pelican website

)
also don't forget to ask your indi to re- foam the flaps.
too bad i live on the wrong side of the country

would love to give you a hand with that project.