It it’s that old, it probably has lots of lead in it, and you probably shouldn’t use it.

Eh, leaded solder is just fine with some basic precautions (and still indicated for military and space ratings) but the smell is probably a highly reactive core flux (rosin) that will eat away at anything it's used on and needs to be vigorously cleaned off after soldering. It may also be a sensitizing allergen so maybe kabdib shouldn't use it, at least not without an extractor.

If you're doing more than the once a year small project you should have fume extraction, occupational (or hobby-based) asthma sucks. As does metal flu (zinc for welding and tin for soldering although I expect that's rarer).