from what ive been told my engineer is that to install a LS1 in NSW you must have a full length chassis to big mods
and all the usual emission stuff from that motor.
i will be starting my 304 holden motor in my 240z (VT SS commodore motor) but stroked out to 353.
and that my engineer will sign off on with upgraded front brakes not rears so they can be drums and must have all emission stuff on the motor and exhaust eg cat convertor and charcoal canisters
hope that helps but ring around and most are willing to give you the right answers
p.s what engines you can put will depend on the engineer all have different opinions so find the one that suits you
peter