I have weighted it, 3.5 kilos, 8cm height and 10cm diameter. 5 ohm primary resistance and 2 x 0.45 ohm on the secondary windings.
Looking into that web page, it's between 300VA and 500VA which makes sense considering the total audio power.
Assuming 350VA, 32V in secondary, I am looking to have it correctly operating at about 10A under load?