Hello Erick,
The point dwell for a 280-SL with factory transistorized ignition unit when installing new points is 30 deg. plus or minus 1 deg. The point dwell range for used points should be 30-36 deg. (Mercedes Technical Data booklet 1972, p213).
The engine timing could vary according to the engine version and distributor. With standard compression and the 0-231-116-051 distributor with the factory transistorized ignition (8 deg BTDC at starter speed withOUT vacuum)(2 to 4 deg. ATDC @ idle with vacuum), (12 to 15 deg BTDC @ 1500 rpm with vacuum), (30 deg BTDC @ 3,000 rpm with vacuum), (30 deg BTDC @ 4500 rpm withOUT vacuum). These figures will be different for a 1971 USA delivery W113. (1972 Mercedes Technical Data booklet p. 214). If your car is a 1971 USA emission engine let me know and I will list the specs for it.
Joe Alexander
Blacklick, Ohio