Your amp is very similar to mine as all the transformers and those blue caps still date from the blackface era, except possibly the PT which is close to the beginning of the drip-edge. It would have been possible to swap the cover, but I believe that BF transformers had plastic wires and cloth board wires, then that reversed for the SF era. Yours is transitional with the old caps and transformers and plastic coated wiring, but the transformers would have still probably been plastic covered wire. To me, the wire colors of the center taps look a little strange so it is possible that somebody replaced the PT. Mine are dated a bit earlier and the pics are on a different PC. The only printing I recall seeing on the inside of transformers that old is CSA so I can't say for sure whether that's original or another part number from a replacement. Either way that's a huge score.