I guess if you are reading this, you want more out of your Blazer. Be that HP or more miles per gallon. Guess what ! By having better performance you make your engine better, which in turn takes away more restrictions and if you kept your foot out of it (Disipline)your mpg will go up.
Now lets talk camshafts. First you must decide on what kind of power you are looking for. Stop light to stop light, 0-60, street, dragstrip, Bragging rights but no streetability, and daily strong driving. When you make up your mind, start calling all of the big Dawgs , Comp, Lunati, and the rest. talk to the customer service guy's and tell them what kind of driving and your anticipated HP. They will all ask you about your torque converter. This is perhaps the most important thing that they need along with your rear ratio and what rocker arms that you will use.
Camshafts and torque converters go hand in hand. Stall speeds , lock up, no lock up, Nitrous, Supercharged, Turbo and compression ! All need to be considered.
Replacing the General all around , made for the masses, camshaft is probably the single most performance oriented thing that you can do for your engine. But remember that it also involves your converter and rocker arms. At the least.