Consider
http://www.bgsoflex.com/megasquirt.html as a replacement ECU and going back in time to the reliable D-jet electronic injectors (e.g., on a 1972-73 450SL). Of course, if you're subject to CA smog checks, you'd need a blind examiner . . . .
M D "Doc" Nugent
My 350SL (5.6) project