Thanks Blue Bowtie,
Interestingly the marinized LS1 that I have seen has the ports for the precatalytic oxygen sensors and doesn't use them. It would not be that expensive to set up that way and the motor may run better. I am aware that there are dummy post catalytic sensors that give a false OK reading to the computer.
Basically I am on a budget and am trained in the mechanical field so that I do what ever I can myself.