^Um...waaaaaaaaay off there.
L67 1997-2003 LIM will be just fine if you machine the outlet some as stated above. Unless you want to run the 2004-05 LIM with no machining required, then go for that. Most machine shops will charge about $15.00 to $20.00 to do this service, its easy to machine it.
You will for sure have to run a GenV SC gasket, and depending on your throttle body, yes, for sure you will have to run some sort of adapter plate so they mate up. The '04+ had a 4 bolt TB that was electronically controlled, ours must remain cable controlled. How it should be IMO.
The SS M90 kit for a GenIII wont work correctly with a GenV M90. It wil bolt up yes, but will not be cooling all the out let air from the blower because the opening of the GenV is a little bigger, and moved forward to the edge of the rotor assembly, and on into it, where on a GenIII, shorter, and stops at the rotor assembly.
~F~