Timing chain breakage is almost unheard of on the M119. Have you pulled the valve covers to confirm this is accurate? Or confirmed the exact damage to the engine? it may be fixable, which would be the preferred option of possible.
If you do need a replacement engine, and can't locate one from another E500E, then yes... a 119.972 motor from a 1993-1995 500SL/SL500 is 100% bolt-in (need to swap the ETA though). It MUST be those USA model years and MUST confirm the engine serial prefix is "119 972". The earlier 119.960 and later 119.982 engines
will not work.
If you buy a spare engine, take the time to do ALL the preventive maintenance prior to installation. All external seals including front & rear crank seals, replace ALL upper chain guide rails (not the chain or tensioner though), replace/reseal the cam advance solenoids, drop the oil pan and replace the oil level sending unit O-ring and oil sump pickup rubber boot, and more stuff I'm forgetting. You will not want to do this with the engine in the car. Also remove the transmission and re-seal that as well (
every single external seal, especially the front pump and converter seal). Check/replace the reverse clutches while it's apart for the reseal.
BTW, welcome to the forum!