Serial Mac to Serial PC works fine with a crossover cable, I've done it, run a terminal program on both and you should be able to transfer your files . . .

. . . who really cares how long such a transfer takes?

IIRC, you can do modem to modem the same way with the proper cable pinout, but I've never done that. If you have access to two phone lines or a friend or a pair of friends with wired telephones, you can use the modems do do a ZTerm x-fer directly, circumventing the need for a dialup account.

My favorite cross-platform and cross generational Mac option is the ZIP Drive, I think I paid about $3 ea. for three USB versions at thrifts. I still have my two original drives from their first release. That's probably the easiest SneakerNet solution available, unless you have a SCSI CD Burner.

I've got two or three extra SE/30/IIsi EtherNet Cards if you want to borrow one, but finding a pair of ZIP drives and a disk would cost less, or ever so slightly more, than shipping the card both ways. Since you might have a PC SCSI Card, you should only need one SCSI ZIP. They also came in parallel port configuration, IIRC.