Yes, you need to connect them together with a cable and with termination set up as you would for any other device connections.
On the target (emulated/RAM disk) machine, you need to run that 8xxtarg program, which isn't a TSR or anything, it runs in the foreground, so it ties up the whole machine. Maybe it can run under DESQview or Windows 3.x or some other multitasker which doesn't mind a program directly accessing a PCI device, or maybe it can be run in a virtual machine with PCI passthrough, I don't know.
8xxtarg is pretty ugly, it prompts you for some non-obvious parameters on startup like the SCSI bus clock speed. I'm not sure how much some of the matter though! It will let you save the RAM disk to file but it's a non-standard disk image file format, I think it was something weird like a normal disk image but with a CRLF-terminated line at the start containing some disk parameters, or something weird like that. It could probably be made a lot nicer without too much work. I've been meaning to get in touch with the author of this post to see if they ever improved it. I would really like it to show some information about activity and throughput, allow the settings to be specified on the command-line, use normal raw disk images, and perhaps do I/O directly to a file so the entire image doesn't need to be in RAM (let SMARTDRV or something do some caching for me).
I've used 8xxtarg mostly with a Symbios Logic SYM22801 card (based on the SYM53C876 chip). I think I have a card with a 53c810 on it which I haven't tested 8xxtarg with so much, if anyone is thinking of buying one of those I could double-check that it works.
What kind of use cases are you considering? I might have some advice I can offer about whether I've tried that myself, or might be able to test it for you.