As regards techs in the Boston area, be advised that at Foreign Motors West in Natick, MA (a dealer), there's a tech there who drives a 500E. His name's Paul Lussier and his phone's 508.903.5311. Give him a try, he's an exceptionally good tech.
Tom, actually Porsche did nothing to the 500E motors. The motor's the same as the 500SEL motor (the SL had a different injection system initially, but after '95 or so went to LH injection) except it does have 500E-specific cams. Porsche did the modifications to allow the installation of the 8 cylinder motors & larger transmissions, installed those components (at their Rossle Bau plant, where they'd previously assembled 959s), and did final assembly work. Porsche also did much of the chassis/suspension development work.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car