I did that for 'tuning clicks'. 220uF *just* did the job - I'd recommend 470 or more. My original (banjaxed) raduino was drawing excessive current, though still under 1A, so my 47E was 2W (what was to hand). My new (un-modded) raduino runs cool anyway, but I left the R and C in place - insurance? Swap sides for the 7805 is pretty much a given.
Mike, have you considered a 500E pot for display brightness, or a switchable resistor, in series with the (series) LEDs? The existing resistor is marked 111 - I presume 110E - so something of that order (shouldn't need to be wire-wound) would give a useful 'dimmer' for less-intrusive night-ops.
73 de ZL2DEX
