I would put the large spools of thread in a container behind the sewing machine and thread it up as usual. Try it out and see how it goes. My two straight stitch only machines will use any thread I use. I think any machine will use any thread. The tension may have to be adjusted. I think the people are the thread snobs, not the machines. I have never seen a date on thread. You should be able to determine if it is old if it breaks often.
You got a great deal and I hope you enjoy using all of it.