We use Vintage on most of the rides we build but prefer the Old Air Products for AD's. Fits up under the dash better, retains full size glove box, and can get with cable controls rather than vacuum or electric servos. Both have the same performance and price. Your LS should have a serpentine pulleys and belts which shortens the length of the engine and gives plenty of radiator room. Has been done thousands of times so a search should provide detailed pictures and answers.
I much prefer Old Air Products as well because their customer service is a lot better. On my last project I was trying to set up a slightly unusual system and when I called vintage air they rudely told me that all the info was online (what I was looking for was not) and any idiot can install it. In contrast, when I called Old Air products, they put me in touch with one of their technicians who was knowledgeable enough to understand my question and was willing to send me some documentation on their system that let me be confident that I could modify it to do what I wanted.
When I got the Old Air kit, it matched the documentation and everything went smoothly.
So yeah, Old Air Products has a pretty much permanent customer here. Not so much for Vintage Air.
