Bosch to Bosch "fits" almost every time with the possibility that:

You might have to grind a lip off one mounting boss or add a stack of washers (can't remember which has the lip...240 or 740)

Will have to swap pulleys.

As mentioned above, likely it is a much higher output alternator so now would be a good time to upgrade the two big red wires (alt to starter, starter to battery). All my older 240's had some level of internal corrosion on these wires anyway, so it is a good thing to do no matter what. Same for the battery ground wire.

Check the alternator ground wire intensively while you are down there...again, common hidden failure point where the wire fails inside the ring terminal on the chassis side. Can't see the failure but it sure can give your troubleshooting headaches.