replacement rectifier -- currently 5Z4P is 5AR4 OK

I have a pair of nice monoblock 300B tube amps (Chinese-made, P2P wired, really nice sound). However the stock 5Z4P rectifier tubes are starting to go.

I've been researching suitable replacements and purchase a pair of NOS RCA metal 5Z4 rectifiers. However they run really hot and I would prefer something else.

GZ30s seem to be direct replacement, but hard to find.

I don't have any real specs of the amps and cannot ask the manufacturer if it is OK but do you think going from 5Z4P -> 5AR4 tubes would be OK?

Same voltage (5v), similar current (2.0 5z4p, 1.9 5AR4), similar voltage drop (20v 5z4p 17v 5AR4)...

This is the best I could find as far as a solid answer:
"The 5AR4 draws slightly less filament current than the 5Z4 (1.9 amps vs. 2 amps), and the 5AR4 is rated to be ABLE to handle considerably higher plate voltages and output currents than the 5Z4. Therefore I believe that your sentences I quoted have it backwards." (Going up to the 5ar4 or gz-30 requires much more power
You could put a 5z4 in a 5ar4 slot. It may work putting a 5ar4 in a 5z4 Slot But it may gave very short life.)

Any help is much appreciated...
If you haven't already answered your question...... the 5AR4 will work just fine.
I have a dared sl-2000a preamp., it comes with the stock 5z4p. 
It blows fuse immediately, and seems to spark inside rectifier tube.
i don't have another 5z4p.
i have other tubes around (5u4GB, 5AR4, etc)
is it ok to put the 5AR4 and a new fuse in and try? I don't know if it's simply a. As rectifier tube or other problem.
any advice appreciated.