I would not sand blast anything that holds oil.
Theoretically the sand particles will get stuck in the metal and with heat and vibration will work themselves out. I think that this true, I have blasted something, cleaned it really good, then done some straighting with hammer and dolly and sand still comes out. So, I would be very hesitant to blast an oil pan, even just the outside. If I did I would try my best to tape everything up and clean when done.
On your list, bell housing and heater housing are safe, the rest I would try my best not to sand blast, although if you are very careful you can reduce the risk of contaminating your mechanical assembles, but not eliminate it.
Grigg
