I know people install engine all the time using a lifting plate mounted mounted to an aluminum intake, but I am hear to tell you that using the threads in an aluminum intake is a very poor and dangerous setup. Most aluminum intakes are not cast from high quality materials. The four 5/16" carb stubs can handle the weight easily, but what they are mounted in wasn't designed to hold 500-600 pounds. I believe it's a really good way to get seriously hurt and tear up a lot of good hardware.
Also the shock towers are a lot stronger that the top of a fender.
