My i3v from 2014 came from MakerFarm with PLA extruder parts, and I've used nothing but PLA for them when I've printed replacements. I prefer PLA for them since I believe PLA is more rigid at lower temperatures.

The main question is whether or not you have one of the older stepper motors MakerFarm used to use. They weren't a good fit for the printer application, and tended to run very hot. Those motors are labeled as type 42BHH48-050-24A. If you have one of those, I'd consider a stepper motor cooling shroud regardless of the block material. I did have one PLA motor mount soften on a very long print with one of those older motors.

Heat from the hot end really shouldn't be an issue if your hot end cooling fan is doing its job.