First off, I don't think you can remove the housing without removing the distributor first....because of the way the gears mesh...but I may be wrong on that...never had a good reason to try to remove the housing without removing the distributor first.
There is really no reason to not remove the distributor, before removing the distributor housing, IMO. The distributor is going to rotate, when you remove the housing anyway. Then when you go to stick the housing back on, if you don't have the distributor positioned correctly (which you won't know for sure, until you stick the housing on the back of the head), you will have to pull it off and that is going to mess up the RTV that you just carefully put on the back of the head and/or housing.
My suggestion....simply rotate the engine to TDC, check the distributor rotor, to see if it is at TDC on #1 or #4 (depends on where the rotor is pointing). Make a note of which one it is. Remove the distributor. Remove the housing (there are 3 bolts). Clean the surfaces and oring. RTV the surfaces and oring. Stick the housing back onto the head. Torque the housing bolts. Let it set for a day or two, so the RTV will cure. Put a teaspoon or so of clean engine oil into the distributor housing hole. Reinstall the distributor, so the rotor lines up to where it was before removal.