This CIA report from March 1954 describes an "Improved T-34 Tank" at the "V.I. Lenin Works at Pilsen". The report lists Czechoslovakia as the country of origin. This logically makes since as the T-34 tank was produced until at least 1958, well past the introduction of the T-54 tank.
The report describes numerous things but most importantly a "100mm gun" and "air device for eliminating the gases expelled by the gun". This sounds a great deal like the features of the T-54.
The T-54 was most definitely produced at Czechoslovakia, but initial production was done at Uralvagonzavod located at Niznhy Tagil.
It seems cumbersome to have a tank all the way at Pilsen when production did not start until much later there. Also, the report says "are producing", indicating the tank is already in production at Pilsen at this point. So this isn't just some existing T-54 being demonstrated.
Is this report describing a T-34 variant or an T-54?