3.3V I/O with RS-HFIQ board?

[Rob French]

I'm looking to re-host the RS-HFIQ firmware on a Teensy microcontroller that uses 3.3V logic.  It can accept 5V logic input, but it only outputs 3.3V.  My main concern is with the optocouplers for driving the LPF/BPF and T/R switching... I'm not smart on optocoupler circuit design, but I know there needs to be enough juice on the input side to ensure a full turn-on on the output side.  Will the optocoupler circuits in the RS-HFIQ work with 3.3V applied?

(I realize that "re-hosting" involves work, which I suspect will mostly be associated with the interrupt logic.)

Thanks!

-Rob KC4UPR