John Greenland
CVRS Member

I would suggest that you go back to the Nostalgia site and look at the info on a Sparton 303. It is on the page 2 of the pdf. Page one has a 202.

It has the same tube line up on the front end, (a 58, a24a and another 58) , as your 274 and may be able to offer some help.
It was also made around the same time.

Good luck.