Rear mount turbos are nothing but trouble.
I really recommend you give up on this idea.
It will cause you nothing but headaches
Just sell your LT's, get some BBK shorties and flip them
to face forward and mount the turbos up in the engine bay.
My tuner just came up with a twin turbo system for S197's
where they mounted the turbos right by the bellhousing though.
and made it work nice, but still had to figure out all the oil feed
and drain system issues.
You can make what you're talking about work with some good planning
and common sense, but your oil feed and drain problems will give you nightmares.
Democracy is two wolves and a sheep sitting down and voting on whats for lunch.