There's also the possibility of running a LSx PCM on the SBC.
www.eficonnection.com has the setup.
It really can get confusing to decide which EFI system to utilize. I personally am in favor of the LSx PCM whenever possible. None of the aftermarket systems come close to having the level of investment in them that GM put into the LSx PCM. However, do you need all that the LSx PCM has to offer to achieve your goals? I've built EFI systems utilizing a L98 SD PCM. It worked great and this was just a few years ago. So, yeah, it gets confusing and difficult to decide.
What I would recommend is that you focus on achieving your power goals properly and reliably first. After all, EFI is not needed in order to achieve your power goals. Then, I would decide which EFI system to go with. Just factor the extra cost of EFI on the LSx engine into the initial cost since chances are you'll buy a pullout that has a perfectly adequate PCM already there.