Sure seems like a lot of money to throw after a solution that isn't the problem. These Gen II W126's blow mid 40s on a 100+ day running 134a. I don't know what you think the parallel flow condenser is going to achieve since the pushbutton unit switches off the compressor when the evaporator coil reaches 38-41˚ (42-44˚ vent temp). The Gen 1 (Pre-'86) cars are a totally different story.

I'm just waiting for the OP to come back complaining that his $300 coil and $100+ worth of R12 didn't fix his problem.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]