4.3 swap ?'s

anyone done this? how hard is it I know a ford 302 would be easier, but i have access to a 4.3 chevy that's rebuilt for free! and a line on a nice mazda with a blown motor.

I am in the process of doing one,EFI, it shouldn't be any harder than doing a 302, only problem I can see so far is the oil pan and crossmemeber use a 2wd oil pan and you might have to section it if you are bodydropped and don't want a hole in your hood