Forget about the timing marks. The 261 and 235 engines had a variety of different timing marks. Use whatever timing mark you have for setting initial timing. Set the timing on a running, warmed-up engine using a vacuum gauge.
Use whatever flywheel matches your starter (6v vs 12v).
Use whatever clutch assembly that fits the year of your clutch housing (clutch plate, pressure plate, throughout beating). Put in a new pilot bushing (check that bushing out on your transmission's pilot shaft before installing it)
Maybe someone will post a link to an old discussion of how to drill the coolant holes in the 235 head? There is a recommended drill angle.
