Welcome.
Useful information:
Download a Factory Service Manual (FSM). http://www.xenonzcar.com/s30.html
Download electrical schematics for your car. PDFs are easier to read than those found in books. Some are in color.
Buy the book How to Restore Your Datsun Z Car by Wick Humble. It will save you hours of searching for "how to" info.
Focus on searching Hybridz as 99% of questions have already been addressed. Start bookmarking Z car parts suppliers.
For SU carbs, parts and instructions go to Ztherapy. Buy the "Just SUs" video.
Remember these are 40 year old cars and will need restoration to be safe and drivable.
Join ClassicZCars.com website and search there as well.
Become well informed about modifications before asking questions. People will be more inclined to answer informed questions
Search the forums.
Read all of the new member guidelines and FAQs
Links:
https://www.datsun-240z-upgrades.net/ Recommend the headlight relay harness
http://zhome.com/
https://www.zcar.com/
https://www.classiczcars.com/
http://www.zcarparts.com/
http://www.arizonazcar.com/
http://www.jagsthatrun.com/index.html
http://www.ztherapy.com/
http://www.xenonzcar.com/reference.html