As others have already stated... too many variables could be causing your engine issues.
BUT, if you want to start troubleshooting and resolving engine issues, I suggest you get some basic hand tools, a timing light, vacuum gauge, multi-meter, and a compression tester to start with. You then need to educate yourself about how to tune/troubleshoot a Chevy V8 engine (with an HEI) and also learn how to tune/adjust a Holley carb. There are many online articles and videos that could help (... but be warned that there is also some really bad info on the web). There are also a lot of good books on these subjects. Search out any local car groups in your area to see if any members can give you some guidance.
Question: When you say your engine dies when you put it into drive and give it gas, does the engine completely die and you have to restart it? ... or does the engine bog/hesitate and then begin to accelerate? A bog or hesitation could be as simple as a carburetor pump/squirter adjustment.
But many other items could also contribute to your engine issues... poor/improper ignition timing, bad spark plugs or wires, vacuum leaks, improper carb adjustments (float level, idle mixture, transfer slot, power valve, etc), not running 12 volts to your HEI, stuck mechanical advance weights, and clogged fuel filter are but a few that are easier to resolve. Engine issues could also be caused by a worn timing chain or low compression in one... or several cylinders (bad rings, valves, wiped cam, stuck/bad lifter, rocker arm adjustment, etc).
So if your up to the task... educate yourself, get some tools, and start with the easier stuff first. The more "diagnostic" information you are able to relay to this site, the easier it will be for other members to help.