I own a 1999 Silverado with a 327 5.3 liter V8 and am looking for a 454 big block to replace it. What are the most import parts to have for the 454. Could I buy an old engine block(1977), replace minor parts and still be allright.

this is probably not goint to be easy, you are going to need the computer and all......injectors bigger radiator...etc.

77?? thats slightly old... the older motors were cast iron... so are the newer 454... it might be poosible if u go to an auto wrecker and get the whole motor injectors airbox computer everthing....the injection system on a 454 is totally different from other motors...but for smog reasons u might want to check w/a ref station first