I have the car (E320) and just trying to figure out what parts might be possible to use in the upgrade of W114.
And as carat previously pointed out, W123 brakes would give a chance to upgrade and these brakes will fit W114. Well, somehow at least. Diggin' deeper...
iirc the 320 W124 has a different rim offset to clear the larger calipers than an older 124. So it's likely a new set of wheels would also be required.
You'll need 15" alloys as a minimum to clear the 320 calipers
Ask yourself why you need bigger brakes. Brakes are there to shed kinetic energy and e = mv². That's why the E320 estate has monster brakes - big load capacity and higher top speed capability due to the bigger engine
If you're not going to drive the car any faster you could argue you don't need bigger brakes. But then, if you're not going to drive the car any faster, why do you want to change the engine?