Remind me to try that out when I have a Pentium III one day again
Though to be clear, you're pretty much right that there's no perfect Dos-games computer or a Dos configuration. There is, however, a working middle that covers more games than either of the weak 386/486'er or strong Pentium 3/4'er and better.
Pentium II with 400Mhz is also certainly a better "middle" than a Pentium III with 450Mhz. I had both those systems myself for a period of time and could try out a good variety of Dos games on them, and while the P3 450 was very good, Pentium II 400 was a bit better in few cases regarding Dos-games. But Pentium III with a 8MB Ati Rage3D was better for stronger Windows 95/98 games. Both of them 'did' work with all Dos games I could try on them, through slight fiddles on config.sys and autoexec.bat files sometimes if required, though very little-demanding games like Corncob3D might have been a bit too fast on them.