Five or six years ago, I bought a lot of three ThinkPad R40 Celerons sold for parts, hoping to get one useable machine. I did, ending up with a rather pedestrian LXDE Linux laptop.
Just this week I got a second one running with a whopping 256 MB of RAM, and put OS/2 (ArcaOS) on it. It’s quite a snappy machine. Loads of fun.
Try 63/37 tin/lead instead of 60/40. 63/37 alloy is eutectic, meaning its melting and solidifying temperature is the same (183C). 60/40 has a semisolid state around its melting point (~=190C).