Welcome to CHR WheelieJeep. As a JEEP owner ('05 TJ lifted) your WheelieJeep name caught my eye! Here are a few links to sites that you might enjoy.
Rock Auto, a great source of OEM parts for all models - https://www.rockauto.com/
Summit Racing, a great source of aftermarket parts of all kinds - https://www.summitracing.com/
JEGS, another great source of aftermarket parts - https://www.jegs.com/

For your project, I question the choice of the 318 as your platform as it's an old school base. In the day, the 318 was a lower tier workhorse surpassed by the 383, 426 and even the 440. With a 2000 WJ as your base I would think that sourcing a takeout package from one of the later JEEP/Chrysler/Dodge platforms would be a better choice. One of the late model HEMI's, complete with transmission, computer & harness would be a drop in for your WJ and would be a screamer!