There's no harm in adding a 47 ohm resistor in series. It's functioning as a mild current limiter. A 5Y3GT is rated for 125mA. If you are gonna run it at close to it's limit, then you want a smaller 1st stage cap. 20uF is what is shown as a typical value. A Champ draws what.... 40ish mA? That's an easy load for a 5Y3GT. 47uF isn't gonna hurt the rectifier at this current load, but it isn't really necessary because you aren't causing excessive ripple. A 47 ohm current limiting resistor isn't really necessary either because you are in no way stressing the rectifier. There's the rub with tube rectifiers. As load increases, you typically wanna add more filtering so as to reject ripple but tube rectifiers have capacitive limits. Look at some hifi tube circuits. You might find a SS rectifier with 1000uF. You won't find a tube recto in any current hifi tube gear.
A Champ is always gonna sound thin because it's simply a low power amp. Your best solution is probably a over-rated speaker that will reject cone breakup. A little more B+ to the preamp tubes will get you a little more punch. To me, the lower the wattage, the harder it is to make sound good. Probably because louder amps saturate your ears and everything starts to sound the same. A good power supply is worth it's weight but often times with geetar amps, we only want just enough.