Ken,
Your spring is adequate for the job but is significantly shorter in coils then the original stock spring shown in my earlier post on the NOS M38 engine.
The "U" Shaped hunk of black rubber right below the letter "Q" is the front mount rubber. There is one on each side of the front of the engine. They should only allow the engine to flex in it's mounts about 3/4".
Ok. I was able to find those. Not sure exactly what they should look like, but it seems like they are rock hard. Is that what happens if they are worn out? Would that cause it to rock?