Had a few of these, back in the day.
There should be no damage to the logic board or the transformer. There will be a large number of fried components on the analog board though. Make sure you check the power supply rectifier diodes and chopper transistor as well as the obviously damaged parts.
[edit] be very careful how you power it up for the first time if you decide to repair the board yourself. Ideally, use a variac. If you don't have one, an old TV techo trick is to put a 100w light globe in series with the mains (might want to try 60w for 110v?). If "bad things" happen when you power up, the light globe will come on brightly and hopefully prevent everything getting blown up for a second time. If the globe glows dimly and the Mac boots, it's all good!