I assume you mean the standard one puts out 120VAC, which yields roughly 170VDC only after rectification and ripple filtering.

Yes, a 1:1 isolation transformer will get you approximately 170 DC minus 1.4 volts for rectification and such. Short of using a Variac or winding a custom transformer that seems like the easiest path. You still need to allow for a center tapped secondary so you can get both rails.

 

The problem with an isolation transformer is that the peak voltage is barely adequate. The average voltage is going to be significantly lower. It's an awkward problem without resorting to a custom transformer. I believe there are still a few custom winders around in the US, particularly for toroids.
An isolation transformer designed for 50 or 50/60 Hz use could, with care, have 120% of its nominal primary voltage applied at 60 Hz (by using, for example, a small transformer with a 24 VAC secondary as an autotransformer to boost line voltage - messy, but doable). If the TS is in a 50 Hz country, that possibility is struck off.

I'm guessing the TS is planning on doing something like generating 120 RMS VAC and consequently needs 170 VDC at pretty much an absolute minimum.

 

I believe there are still a few custom winders around in the US, particularly for toroids.

These guys are good, and may even have what the TS is looking for .
http://www.antekinc.com/

 

These guys are good, and may even have what the TS is looking for .
http://www.antekinc.com/

awesome thank you