Hi Bobby,
One place you could concider looking would be Ebay. They have lots of old radio chassis' up for bids all the time, including Philco Cathedral chassis. You might want to do some research though, because like the rest of the guys will tell you, not all cathedral chassis' will fit in all cathedral cabinets. Type in Philco cathedral radio in your browsers search engine and start looking for pic's that will match your cabinet and that will give you a rough idea what model yours might possibly be. Some cabinets do have numbers and such that can be reference points written on the bottom of the cabinets or the inside bottom, but that is hit and miss also.
Good Luck,
Tony
Chuck Schwark has a rather complete rundown of the tube placements (ie chassis) for most of the Philco models up to 1937. Right off hand I do not have his url, but it is listed in the "links" here on Nostalgia Air.
: Looking for a Philco Cathedral chassis, chassis needs to be complete of all parts with speaker, does not have to be working, any model as long as it is a Philco Cathedral chassis. Any help in locating this item would be greatly appreciated, Thanks !