Agree with David12 comments about the differences between the Ref 3, 5 and 5 SE. I owned all three and currently still own the Ref 5 SE. The only caveat I have is that all the ARC Ref preamps require that the input impedance of the amp NOT be less than 20,000 ohms.
I too never heard about a Ref 3 SE model, although I understand that ARC made about 2 dozen Ref 3 LE versions, which had upgraded coupling caps.
I am a big fan of ARC gear. I suspect that any of the Ref preamps will match just fine with the rest of your system, which is very impressive. Just confirm that the Pass input impedance is over 20K ohms.
Btw, ARC just released a Ref 6 preamp. I surmise that the release of the new model will put a downward pressure on preowned Ref 5 SE pricing .... but in any case, if you can stretch a bit, IME, I would recommend the Ref 5 SE.
Cheers,
BIF