Sounds like a great gift! We'd recommend you start with purchasing a Chilton Repair Manual for your Chevy's specific engine size. Next find a local wrecking yard which has an intact engine, obviously with all the necessary emissions components... and do a swap.
One thing to pay particular attention to is whether this Chevy 4 x 4 is a California Emissions Certified truck or a 49-State Emissions truck. You will only need to install the emissions components required for your particular engine emissions specifications. The Chevy dealership should be able to look up this information using the vehicle VIN or Engine Block number.
