Arch from existing install or VM, how easy is it?

[Linux for blind general discussion]

So I'm looking at the Arch wiki currently, and wondering what the 
easiest way to achieve what I want is.

For context, I have a Solus install, in /dev/sda I have /dev/sdb as a 
2.7T drive with nothing on it, no partitions, no file system at all 
going by lsblk

I have a 16g qemu VM (thanks quickemu) that boots up fine in qemu as well.

I've read over the pages about installing, installing from an existing 
Linux system, and moving a VM install out of that VM.

Which would be the safest option, bearing in mind Solus's quirks about 
how it does things, to get a working, bootable Arch system?

What I'm after is putting Arch on /dev/sdb and using that 2.7T of space, 
preferably without having to shut down and reboot from a USB stick. I 
ruled out the replace an existing OS option in the install from an 
existing Linux install, mostly since I like having my fallback option.

So is what I'm after relatively doable? I've gone over the wiki pages a 
few times and am not sure which method will get me a working system that 
I can boot into the easiest.

Ideally I don't want to have to shut down my computer, boot from a USB 
stick and then fight with the install guide because of something I 
typoed, given how typo prone I can be at times