John I am building a pro touring car so pretty much nothing is stock. There are several companies that sell brackets to relocate the accessories if you need to. I am running a Holley Hiram and a glastek 5” Sunoco hood so I didn’t have and clearance issues. Once the motor was my biggest challenges were the AC system (vintage air fixed it) and the radiator. I ended up buying a griffin radiator from summit with both hose outlets on the right side that fixed that. Here are a few random pics of itAce,
If the Muscle Rods mounts work for your LS3, they'll certainly hold down our stock 5.3! On a related note, did you have any trouble with hood clearance? It looks to me like the alternator (with the stock truck accessory brackets) will be too high. I opened a separate thread about it, but I haven't heard from anyone who has used the Muscle Rods engine mounts. Your experience is much appreciated.