There have been a few changes in cam reluctor and crank wheel setups over the years between Gen 3 and Gen 4 motors. The locations of cam angle and crank angle sensors have changed in the blocks. The old LS1 has the cam and crank angle sensor located in the back of the block. The LS1 uses a specific cam with the reluctor trigger machined into a section next to the last journal. It means you need to order a specific cam but you can run any old timing chain setup you like. there was even a gear drive setup available for them.
LS2 relocated all the sensors to different spots. The cam angle sensor was moved to the cam cover and triggers off a reluctor on the cam gear. There were several different configurations of this too over the years with different numbers of poles.
Anyone working on one needs to do their research to be sure they have mixed and matched the right parts.
There's also different versions of crank reluctor wheels with different tooth counts. Important to keep in mind if you ever build a stroker conversion or get a replacement crank.
There's plenty of info available on all the different iterations and what you need to run over on the the LS1 forums like LS1tech.
LS1Tech.com
Cheers