What is physically wrong with the engine? This will help determine what upgrades you do. If the crank is shot and you will be replacing the pistons when you hone it out, you might consider building a stroker.
as mentioned before the TBSS intake is great and there is no need to replace. Replace the oil pan with the C6 ls3 oil pan and pick up as mentioned. The cylinder heads should be 243s and need no modification to make 500hp.
basically on a stock displacement TBSS ls2 all you really need for 500hp is a cam headers and a good air intake.
you may need injectors, I’ll let others chime in on that. I’m not sure if this is common knowledge or not but L96 injectors drop right in and are 50 lb I believe.
My brother is a long time professional mechanic and believes it is bearing seized up.