[morzh]

I would never count on resistor to do the "fuse" duty, though there are those "fusible" resistors today.
Install a properly sized fuse if you want to protect it and calculate your resistor power dissipation according to what it needs to dissipate safely.

BTW, even though there's been quite some time since I held a selenium rectifier in my hands, it does not exhibit the same resistance as a regular diode. Thing is, there are several selenium diodes in series and they have a large Vf in the first place so the battery in your meter may not be able to bias the selenium diode into conduction, and the leakage of selenium diodes is higher, so you will have some finite reading in revers too, hence the high resistance in both directions. You may test it using a transformer and a load, and then see if the proper DC voltage develops.