In my detached workshop/garage, I have an old fuse panel servicing that building only. I am thinking about switching it out with a new small breaker panel. I have been reading everything I can find on properly making this switch, and for a while was referring to this as a sub panel, with the larger breaker panel in my house being the main. I made note of everything I read saying to make sure the sub panel's neutral and ground were not bonded/connected and the dangers that creates. However, upon further inspecting my setup it occurs to me that my situation is different.
The meter hookup is on the side of my log cabin

Years back when I had electric turned on, the power company explained that my 1930s cabin had a really old service hookup: The rightmost meter services just my hot water heater. The left meter goes to my main breaker panel inside the cabin. On the left of that meter is a Square D panel, with a single switch inside that sends a buried line to my detached workshop.
Once inside the workshop, it runs through the pictured rightmost panel with an on/off switch in it (panel is opened up in this photo -- revealing there are 2 black hots and a bare wire neutral).

That switch panel (switch says 100 AMP on it) is then fed into the fuse panel. In the fuse box, the main pull out switch, when pulled out, shows that 60 amp fuses are installed. As you can see from this photo of the inside of the fuse panel, it is a bit of a mess, hence why I'd like to clean things up with a 6-8 breaker panel.
So am I right that this is not a 'sub panel' hookup, since it is coming right off the meter? It is essentially its own main panel in a different structure. I'm thinking I would get a new breaker panel and hook it up to the 3 service wires (2 hot, 1 neutral) present in the adjacent Square D box pictured above?
My comfort level with DIY electrical work is simple swap outs or replacements. If this is more involved I will wait to get an electrician to do it, but where I live up in the mountains, electricians aren't plentiful and you usually have to wait 6 months or more before one can squeeze you in for non-emergency service.
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[5]: https://i.sstatic.net/7bXQ4.jpg
