You were thinking how dreadful it would be to convert an automatic to a manual. I've converted my 190 when I put the V8 in and now four years later I've converted back to a 5-speed. Putting in a pedal cluster is a matter of four nuts on the power brake booster studs and one bolt vertical, all of which are easily done with a 3/8 ratchet, a six inch extension and a 13mm. socket. You have to fish your line to the reservoir through a hole in the firewall and hook it to the slip fitting on the brake master cylinder reservoir. The reservoir has a plugged off fitting there, just cut the nipple off and slip the hose on and refill it. The cluster for a 201(190) and a 124 (300E) are interchangeable. The clutch masters are both 19mm.
Just remember when you buy a transmission that you get the driveshaft as it is different and get the console cover and boot.
Good luck...it's worth the little trouble!
300SE, 300CE, 190/5.0