68030 on a 16-bit bus, max 10MB RAM, no expansion slots so nothing except SCSI.
So, I put 10MB in it, a bigger SCSI HDD, a SCSI Ethernet adaptor on the back, and built both OSes up from scratch.
MacOS 6.0.8 with all the extras: a menu bar clock, hierarchical Apple menu with modular Control Panel, MacTCP, etc.
And MacOS 7.6.1, which doesn't officially support the Classic II as it wants 12MB RAM minimum -- but I had RAMdoubler. OpenTalk, Netscape Navigator 3, Communicator 4, some early Internet Explorer, etc.
Honestly, there was little difference. It was usably quick on 7.6.1 and more stable. So many things that are extras on 6.0.8 are built in to 7.x that it doesn't need that much more disk or memory.
7.x did more, made it easier, and ran well.
But, as an example, on roughly 1MBs ADSL, it took about half an hour to render the top-left quarter of https://slashdot.org/.
Perfectly usable machine, could do email, FTP, Gopher, but forget it on the WWW on of the noughties (2000-2009).
Second this - System 7.5.3 has by far the most backward and forward compatibility of any classic era Macintosh OS.
It's also available for both 68k and PPC architectures. And the PPC version can run 68k software (it internally emulates a 68020)
I was going to say, why System 6 and not 7?
Possibly because System 6 runs better on SE-era machines?
I tried it, about 20Y ago.
It does but not all that much.
I had a Classic II, so a very limited machine.
Not a "road apple" but a "compromised Mac":
https://lowendmac.com/1991/mac-classic-ii/
68030 on a 16-bit bus, max 10MB RAM, no expansion slots so nothing except SCSI.
So, I put 10MB in it, a bigger SCSI HDD, a SCSI Ethernet adaptor on the back, and built both OSes up from scratch.
MacOS 6.0.8 with all the extras: a menu bar clock, hierarchical Apple menu with modular Control Panel, MacTCP, etc.
And MacOS 7.6.1, which doesn't officially support the Classic II as it wants 12MB RAM minimum -- but I had RAMdoubler. OpenTalk, Netscape Navigator 3, Communicator 4, some early Internet Explorer, etc.
Honestly, there was little difference. It was usably quick on 7.6.1 and more stable. So many things that are extras on 6.0.8 are built in to 7.x that it doesn't need that much more disk or memory.
7.x did more, made it easier, and ran well.
But, as an example, on roughly 1MBs ADSL, it took about half an hour to render the top-left quarter of https://slashdot.org/.
Perfectly usable machine, could do email, FTP, Gopher, but forget it on the WWW on of the noughties (2000-2009).