Hi !i have a similar situation but at the opposite site. i have a 250sl with original engine but my injection pump has been replaced probably by the previous owners ( i dont know why and when ). The pump i've got is the r22 , which is typical of a 280se car. 2 years ago i sent the pump for a complete overhaul becauase the car was running very rich ( i sent to hans fritszche in germany , oldtimer technik) . He replaced the space cam with the correct cam of an r18 pump and set my pump accoriding to the r18 configuration. The result is perfect . He suggested me to replace the injectors too but i had a bad experience with r2 injectors ( you can read in the forum if you want ). i have a popping sound when i release the accelerator too , but i guess is something wrong with the exhaust or a small leak near that .
i bought from mbclassic.de a set of new r2 injectors and they were not working at all and i've been refunded. I decided to keep my old r1 for the moment . They release the fuel a bit too early but still within the specs.
