Edcor specs?

[Fuling]

Hi

I recently ordered some Edcor iron to build a cheap IT-coupled PP amp, two XSM15K/15K ITs and two XPP15-8-8K OPTs to be specific.
I´m not expecting miracles from >13 bucks ITs and >20 bucks OPTs but I´ve used their small SE OPTs before and found them very good for the price.

Question is: How much voltage can those coupling transformers handle before they saturate or otherwise misbehave?
I´m talking voltage swing, not insulation strength.
I would like to use triode wired 6CM5s as output tubes but they require -40V or more on the grids and I´m not sure the transformers can swing that high.

I understand that keeping DC out of the transformers is a good idea so the driver stage will be either a balanced PP stage or an SE parafeed thing using the transformer for phase splitting.

Alternative output tubes might be 807 (-22V) or 6AQ5 (-15) but I would definitely prefer 6CM5 (EL36).