Yeah, if you are happy with a small screen, scaler=normal2x will do the trick, I guess. The real problem is not to get "a game" scale pixel perfect with rectangular pixels, because the pixel perfect patch does this perfectly, but the biggest problem is that this patch (and another version I found), do not cope well with the machine=vgaonly parameter. Apparently even some of the shaders for the latest DosBox ECE also have trouble with this setting.
Also the PPP (Pixel Perfect Patch) is not supported anymore in the latest DosBox ECE versions, which is a pitty, because it works great for other games that don't need the machine=vgaonly option.
I'll try out Lemmix, thanks for the tip, but I'd really like to get my old CD (with CD audio ;-) ) running too. I'm a bit frustrated that something seemingly so simple, is so hard to do in DosBox. At this moment I think a custom shader for dosbox to mimic the behaviour of the pixel perfect patch, is my best option, but I didn't come across a shader that does exactly that. The "pixel perfect" ones out there, require an exact 4:3 aspect ratio and can't handle a 5:4 one... :-(