[mongocanfly]

Im not sure what your reading on crossmembers... but with adapter plates a LS will bolt right in where a smallblock does and use the smallblock motor mounts...you may need to swap/modify the oilpan for axle clearance though...

And No...dont use your stock fuel lines...you'll need to upgrade to high pressure fuel lines...I have my pump p mounted above the tank and it works just fine...I'd keep it as close to the tank as possible....you'll need a return less fuel system to run the vett reg and you'll need a return port back into the tank no matter what...you can modify your tank for a in tank pump but I'm not dealing with dual tanks either...