[Amps] Another Transformer Question

[k7fm]

Speaking of parallel transformers - here is another:

Wishing to build a 400 watt am transmitter out of existing stock.  All parts 
accounted for except a modulation transformer.  On the shelf are two ART-13 
modulation transformers.  Together, they will put out enough power to easily 
modulate 400 watts.

As long as I match impedance ratios, is that any problem of simply 
paralleling them?

And, if I use parallel or push pull finals, can I use separate modulators 
fed from a common source to modulate each final tube separately?

All, right, this is an amp forum - so rephrase the question to apply to the 
final of an am transmitter (we can leave the exciter out for purposes of 
this forum).

Colin  K7FM