Behold, Biz WD=?ISO-8859-1?B?2A==?=HCO signalled from keyed 4-1000A
filament:

After 31 years and a bunch of parts in the garage, I am finally building
my dream CW receiver from scratch.

Awesome!! I have a beautiful all-tube SW RX (my dream too) on the go :-)

Just wondering if I converted the 6.3 VAC filament voltage to a DC
voltage if doing so would be worth the effort to reduce hum.

Yes. As an audio/RF builder, I power all my filaments from DC. For up to
1 amp, a 7805 with two 1N400x in series with the groud pin will do fine.
For more current, an LM4558 driving a 2N3053/3055 in a darlington
arrangement is great for up to about 6-8 amps.

Goos success to you!

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca