Bridge Rectifier for the heater 300b tube amp

No.... Don't do that. If you're looking to truly upgrade your rectifiers with discreet parts go get some boards and build them out right. I've got a couple of nice rectifier boards I'd be happy to give you, but I've only got 2. 

A fully discreet rectifier can be built to smooth and filter the power. Is it worth the hassle? A lot of people think not. It's the way to go if you want the most ideal rectification possible. Some like fast diodes. Some like slow. Some want to tune and filter the stage. That's how to do it. I did what George suggested; 250V, 35A Vishay bridge rectifiers. The heatsinks alone are more expensive than the Vishay parts. 

Can I just point out that if you need to ask the questions posed you probably shouldn't be building rectifiers? 
In all reality, if you want the best, most stable rectification, you want tube rectifiers.