If you check out diyautotune.com site you'll find there is a section with directions on how this guy converted his carbed 350 to tbi. He is using a megasquirt ecm, which you do not have to use, but if you read and watch the 1st and 2nd parts of the conversion, then you'll find all of the parts needed.
In terms of parts, a short list is intake and coolant temp sensors (same sensor), IAC and TPS that is on the GM TBI, and MAP or MAF sensor depending on ecm being used. Fuel pump rated for the TBI you have. If you are using a stock GM TBI, then I believe the fuel pressure regulator is built into the throttle body. Also, if using the stock TBI, then you'll need both lines (steel braided) that attach to the rear, properly rated fuel pump, and a fuel filter rated for the TBI unit (micron size). Now that I've typed all of this, are you planning on using an aftermarket setup or stock setup?
What are you planning on using for an ecm?
And also, if you are running something like Megasquirt, you don't have to swap distributor's, but is highly recommended. Otherwise you have to know exactly what is going on with your distributor in terms of vacuum and centrifugal advance at varying MAP readings. Basically you have to have your old distributor tuned - MUCH easier to bolt on the HEI unit!