It sounds to me like you are on the right track and using the plane should help you figure out if any additional work is needed. If it works well then why alter it? With a few exceptions, run-of-the-mill old tools should be used, if possible, and not just shelved. Most of these were probably churned out by the thousands, if not millions and have probably been altered (fettled, tuned )in some way, even if it was just a sharpening, a name stamp, or the flattening of the sole that nearly all wooden planes needed throughout their lives. Don’t assume the previous owners tweaked them for the better though because a lot of folks would just take a stab at it and then just give up if things didn’t work out. Wooden planes do move some with moisture changes and the soles and boxing tend to wear. That is one reason why a lot of these old tools are still with us.
We all go through a learning process and I find myself returning to some of the tools I have had for a while to retune them based on new knowledge or maintenance. A person has to know their limits and if you don’t feel comfortable doing the work you can always go back to it later. Best to do the minimum and revisit the tool if need be.
When I first got interested (many thanks to Roy Underhill) knowledge about hand tool woodworking was nearly impossible to come by and we are truly living in a golden age of information about the subject. Learning about the craft, the associated history, the personalities, and the tools is such an enjoyable pursuit.
The good news is that there are tons of the good old stuff still available and they are not generally terribly expensive so even if you make a minor mistake you can probably correct it or replace it at a reasonable cost. We never like to loose a tool but tools were made to work. There are a few real collectables still out there and a person should do some research to figure out if they have a true museum piece. In that case you should find a true collector or a museum and replace the tool with a user tool. I have some older pieces and some of the items I have are in demand but they are still just user tools, some more expensive than others but none that can’t be found on EBay if your pockets are deep. So if you are a collector, don’t fettle. If you are a user, get user tools and fettle them as needed and as your skill level allows. If you do both, decide which are your user tools and which are your collectables, and treat them accordingly.
Wooden rabbet planes are a good place to start because they are so useful, simple, basic, and widely available. I think I have about ten of them now (I didn’t go count them), both straight and skewed, and the last couple I picked up were only around ten dollars each.