Hello Alfred,
You will not have a balancing problem with your 280 engine. You will need a 280 manual flywheel since your 230 flywheel is counterbalanced and the 280 flywheel is balanced. The 230 flywheel bolt holes are also a smaller diameter than the 280 flywheel bolt holes. You will also need six 280 manual flywheel bolts which are longer than the bolts for the automatic flywheel.
You can make your 230-SL flywheel work if you take it to a machine shop and have the bolt holes bored larger and have the counterweight mass machined off so that it is in perfect balance instead of counterbalanced. You will still need the longer bolts used on the 280 manual flywheels. It may be easier to locate a good used flywheel or order a new 280 manual flywheel. Your clutch and transmissiion should work fine but don't forget to add a pilot bearing and dust cover to the back end of the 280 manual crankshaft before installing the flywheel and clutch.
Joe Alexander
Blacklick, Ohio
