A very popular conversion.... you will need to buy a euro 300 flywheel - then have it ballanced.

Common 240D 4-spd. bell housing and transmission will bolt onto the 300 block..... yes, you can use the 240 clutch and it wont be over-stressed.

One thing to consider: different final drive gear ratios were used on the 240 and 300..... so you might be replacing the pumpkin as well - otherwise install the engine/tranny combo and see how you like it.

Hell, I've got a 240D 4-speed in my backyard that you can have as transmission and clutch donor for $1200 - if you dont mind paying shipping cost from East to West Coast.