[patrician56]

I think that you will find that your radio already has a push - pull output stage - the 2 - #41 tubes.

Philco offered a number of radios in the 1939 - 1942 era in both table and console versions that offered this "slant dial" chassis with a few variations. Your model uses the same cabinet as a US 40 - 155T, however that radio used an 8-tube layout while your radio appears to have been originally a 7-tube layout. The US model 40 - 150T used a 7-tube layout. The 1 additional tube for the 40 - 155 is listed as a "diode detector".

In any event, these radios perform very nicely and sound great. I had the 1941 model 41 - 255 which has a 9-tube layout, some of which are the "loctal" tubes that Philco was pushing that year. I did it for a friend and he has gotten a great deal of enjoyment out of it.
Check out the service information on the Philco library section of the Phorum site and compare the schematic for the 40 - 150, 40 - 155 and the 40 -180 variations with what you have.