searching for hei wisdom

Alright guys, Paul here again. I believe I now have every thing I need to eliminate the spark control computer and replace it with an Hei ignition.
Quick recap; 1981 d150 slant six four speed. 110k with an unknown history. Runs good. I want it to run better. So I researched eliminating the spark control electronic ignition and replacing it with a GM HEI set up.
OK, looks simple. Found lots of information, great diagrams and a great video on YouTube where a guy kind of shows the swap. Bought GM Hei ignition kit(coil, wiring and module), vacuum advance distributor, spark plug gapper, tachometer and timing light. Of course having all appropriate hand tools and wiring instructions. Also plenty of wires, connectors, heat shrink etc.
Still have a few concerns
Do I need to put a relay in this system?
What do I set the timing to?


And lastly, I am extremely nervous about this. This is my only transportation and I need this done in one day and don't have any experience pulling a distributor, or doing anything with timing. I am searching for more knowledge and information about this. I am very confident I can do this but have no physical guidance.lots of access to information but no Mopar guys and definitely not slant guys. Please be so kind to offer me what information you can. Thank you all way in advance.
If it weren't for you all giving me enough hope to purchase this truck and try this, I wouldn't be here or have this truck.