Do you have a 4.3 already? If not, find a Blazer with a 4.3 and use it as a donor for all of the motor mounts and accessories you will need. A 4.3 is 3/4 of a 350 and most all of the external parts will carry over. The engine is about 5 inches longer, you will have to take that into consideration when you install your accessories and radiator.