The rubber expandable ones are ok. They are mostly used for emergency repairs. We sold those when I worked auto parts counter many years ago, and they seemed to work fine. They don't last forever, but they will last or a few years. I'd keep a spare of the right size with the car, in case I ever had trouble with the one in the block.
They also make a copper expanding plug, but I don't know much about those.
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk