The thread below is a review of my travails in changing motormounts on my 1977 300D. It may prove helpful.
http://www.peachparts.com/shopforum/showthread.php?threadid=24727&highlight=jcd
To answer the question on jackstands,,,,,I ran my 300D up on ramps to gain access. Then jacked the motor with about 3 1.5 ft lengths of two by ten between the jack and the oil pan
I also found that I could access all of screws without lifting the engine. It took a little doing but I was able to get it done.
Send me your number via private message and I'll be glad to provide you with my 2 cents worth via phone.
Jcd