Sounds like you have pretty much a blank slate to start with just a few parts on hand that you may want to reuse?
So maybe you can start with what parts you have? Sounds like you have a converter and maybe want to know how to rewire it to use it to charge some batteries and maybe power some 12 volt items?
Any chance you can snag some pictures of what you have or find a model number on the converter, so we can see what you have?
Those older converters were often built with the fuses or breakers built in as a single unit. they might have called it a load center?
That might make it as simple as wiring the 110 AC to input of the converter and attaching batteries to the output with any 12VDC items you might want to keep running put on the output side of the fuses?
It may have been something like this and what you want to do?
But then add the solar parts to this ? Since solar is different voltages and needs different parts, I thought we might need to get the basic things for what you want first before getting into the solar.
But knowing what you have may be the first step, so tell us more about it?