Doing that "in the chassis" would never happen in MY driveway.
 
	That engine would come OUT, so I didn't have to work on my back like a prostitute for the whole job.  Flip the engine over on an engine stand, rather than flipping the worker over on the concrete.
 
	Likely get a better job done with the main seal, pan gaskets, etc.  High mileage?  Timing set, rings, head gaskets and valve job.  MAYBE bore + pistons, crank grind, block decking...