[MrFixr55]

Hi DConant
Yes, you can replace chokes with resistors.  You do stand the risk of increased hum.  the solution is to increase the capacity of capacitors.  This is often done when one cannot repair a Field Coil speaker and replaces it with a speaker that uses a permanent magnet.  If you are describing the 400Ohm choke, labeled #120 on the schematic, you may want to increase the capacity of Cap #62B to compensate for the filtering that the choke provides.  My rough guess (the more engineer-oriented experts can chime in) would be to double the value.  Based on the location of this choke, there is no need to change the capacity of other caps.  The issues and pros vs cons of changing or upping the capacity of filter caps is this:

• PRO- The more capacity the less the AC "ripple" of the supply.  Newest generations of tube equipment have caps as high as 50 - 80 uF.  Power supplies for solid state equipment have capacities in the hundreds or even thousands of uF.
  
• CON- Since caps draw current when used as a filter, especially as the first cap after the rectifier, increasing the capacity increases the voltage, and the current.  Too large a capacitor in the "input" position (directly across the rectifier with no choke or resistor) can cause a current draw that exceeds the capacity of the rectifier or power transformer.  
  
• PRO- the higher the capacity, the less need for expensive chokes (inductors).  Just price caps, resistors and chokes on the resale market.  The first filters were paper caps, which have the lowest capacity / size ratio.  Wet electrolytics had a higher capacity / size ratio.  The latest electrolytics have the highest capacity / size ratio.
  
• CON- Increasing the size of the capacitor increases the output voltage of the power supply.  This may affect bias, violate maximum voltage specifications for a tube, cause excessive current draw, etc.
  

Since the specifications for electrolytics 'back in the day' was -20% / +80% increasing the cap value by 50% is likely not an issue.  Voltages should be within 20% of specifications.  For some (but not all) circuits, measurements with modern DVMs may not match the published readings that may have been taken with meters with sensitivities and loading of as low as 500 ohms per volt, etc.

Regarding the "Selectivity / Fidelity" adjustment and peaking the IF, I don't think that a dip between 2 peaks will cause poor fidelity.  the concept was to have as wide an IF bandpass for fidelity, but a narrower bandpass for selectivity.  People on this Phorum who have experience as Radio Station engineers can comment with more authority than me, but I believe that the fidelity of AM stations have decreased on purpose with the movement from music programming to talk programming.  It is likely that the set was designed to narrow the IF bandpass to attain greater selectivity on shortwave.  Sets having variable selectivity / fidelity settings either by a separate switch or incorporated into the band selector were designed to either widen the IF bandwidth to gain better fidelity at the expense of adjacent station rejection or to narrow the bandpass to reject adjacent channel interference.  

My comments are based on general knowledge of electronics and audio, especially vacuum tube circuits, and analysis of the schematic.  Sadly, I do not own one of these sets because it looks like a great set both aesthetically and electronically.  Owners of the set, please add additional comments.