The problem with wiring diodes in parallel, especially diodes whose current ratings are so much less than what's needed, is that they have slightly different forward voltage drops. The one with the lowest voltage drop is going to get the bulk of the current, and it could overheat and cook. Which then shifts the current to the surviving diodes, and the surviving diode with the lowest forward voltage drop... and so on.

There are 50-100 amp diodes available - just not at radio shack. DigiKey has 75A 1200V power diodes available for $4 each. (PN RHRG75120-ND). Four of those would do you, assuming the forward voltage drop isn't too high. They also have 200V 50A bridge rectifiers (pn MP502W-BPMS-ND) available for $5.60 each. If you tripled up on the 50A bridge rectifiers, you would have a decent chance of getting a bridge rectifier that would last.