Mesch, if you just want to get the amp up and running, you have to fix the power supplies. The 525V main filter can is available from Antique Radio Supply in Arizona. You will also want to replace the bias power supply caps and the attendant rectifier (the original is a selenium; selenium rectifiers should be replaced when and wherever they are encountered).
If you do those things correctly its likely that the amp will run fine if the tubes are OK and it was otherwise operational when stored.
If you do those things correctly its likely that the amp will run fine if the tubes are OK and it was otherwise operational when stored.