Duke offers a very good reply. You just can't beat inches for adding power.

If you want to feel better about your cars power, go find a friend with an automatic transmission 240D and trade cars for a few days. Afterwards you will feel like you're in a rocket ship. Everything is relative.

The first gear start would be the only thing worth pursuing without changing engines IMHO. If you were going to change engines, I think it would be more practical to change cars. There are a lot of 300E's out there that are still in good condition.

Good luck,