Testing a normal Linux installation sounds like a good idea. In my opinion it’s better to transition to Linux than switch. That way you can go back to your previous system setup and see what you are missing or need without having to open your computer and swap hardware. If you can add the old or new SSD as an external drive and so that you can can boot then your plan might work out.

I just can’t be bothered to switch when my current distro worked just fine for me for the last 20 years. I have no time to experiment anymore, I just want to get things done.