There is some question about the parafeed capacitor value for the Paramount, so I am putting up this summary. Unlike the Paramour/Stereomour situation, the available iron options are all very similar and call for similar parafeed capacitor values.
First, the voltage rating should be a minimum of 600v. We've never experienced any problems with 600v caps. I recommend a minimum 85 degree C temperature rating; some people have used lower ratings without problems but I still can't recommend doing so.
My rule for choosing parafeed caps is 2*L/(R*R) where L is the plate choke inductance in henries, and R is the output transformer nominal primary impedance in kOhms; the result is in microFarads, uF. Usually a range from half to twice that value will give pretty good results, and I've posted periodically about some considerations that might make one lean towards one end or the other. It is something of a compromise between small-signal bandwidth and power bandwidth.
A much smaller cap will reduce the bass extension. A much larger cap won't hurt anything; it is always at least equal to a series feed transformer with the plate choke's inductance.
Here are some examples:
Paramount, stock iron, 2A3 or 300B: 24 henries, 3Kohms, nominal 5.3uF, range 2.7 to 10.6uF (ships with 3.3uF)
Paramount, Magnequest upgrade iron, 2A3 or 300B: 27 henries, 3Kohms, nominal 6uF, range 3 to 12uF