One of the key things to remember with a Small Block Chevy (SBC) is that, yes there is a lot of interchange, but no, not everything fits every year of engine. So, while you technically can use ANY short block, you can't use any heads, oil pan or intake on any SBC as some things were changed over the years. You will need the later heads with the 3 bolt holes in the ends for the late accessory drive setup, and you will probably want to either go with a late serpentine accessory drive, or a V belt one for an R-4 A/C compressor as these parts are the easiest to find. Within that though there are myriad little details you will have to conquer like hoses for power steering, A/C, etc. Just be sure to get a complete accessory drive setup from one complete car, and pull everything down to the bolts. Some fasteners will be specific to a certain job and were made for GM especially for it. Hardware stores will not be able to help you if you do not carefully remove (and preferably label) the bolts. As for engines, I like the 327 for a lot of reasons, but for a first timer go 350. If you don't use a 350, be sure to get a engine with a minimum of a 4 in bore (302,327,350,400) as smaller bores will restrict breathing.