If a 996 engine is to be stroked 2mm using ti rods the timing gear shaft needs to be trimmed a bit to clear the con rods.
Trying to make standard 996 cases to fit a bolt on deep sump is a mission. Lots of machining and just the magnisium pick up pipe and special oil filter together is near 500 quid plus the mag sump and machine work to make it all fit.
If your looking to build a bomb proof bottom end then this could be a good idea -
http://cjsracing.co.uk/Bryan%20Jacques.htm