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There is an unofficial (this is not a Microsoft product) "MS-DOS 7.1 China Dos Union" compilation here: https://winworldpc.com/product/ms-dos/7x
Members of the community have found this useful as it includes DOS utilities, various extras, and a friendly setup program.
The PS/1 was 286-based, wasn't it? "MS-DOS 7" needs a 386. (But *PC DOS* 7 and 7.1, from IBM, are still 8088-compatible—or at least I know for a fact that 7.0 is.)
MS-DOS 8.00 exists as part of Windows ME. The boot disks created by Windows XP etc, contain DOS 8.00, even though the DOS emulation is DOS 5.00. XCOPY uses unicode, which means it does not work without windows loaded. However, the 7.1 version can be fixed to that end. www.Multiboot.ru is the goto source for this.
It even has my help file in it.
I know it's been a couple years but there does exist exactly what you're looking for on the multiboot.ru site as far as an UNOFFICIAL MS-DOS 8.0 installer ISO:
Specifically the download:
The guy who put that together basically took the latest core files, patched them due to the issue with WinME and then some MS-DOS utilities that appeared on later versions of Windows (up to Windows 7 believe it or not). The list of files the ISO contains are included at the first URL I gave near the bottom of the page.
I'm going to spin up a Virtualbox VM with that tonight and see how it works out.
This site cannot host that ISO because it's not a genuine distribution, so that makes sense. It's basically cobbled together with a patch for the WinME MS-DOS 8.0 core files so don't get your expectation too high. It is what it is.