Can anyone tell me if there are any other models of Philco cathedrals that share the same bottom moldings as a Philco 70?

You could try contacting Steve Davis on the Philco Phourm. He does make different parts for some Philcos. He will be making me a new grill for my 70 since it has many missing sections. I do believe he has about a two month backlog due to moving to a new home.

I bookmarked his pages.

http://www.philcoradio.com/davis.htm

for reference they are the same as models 21, 35, and 46