Used car sales/repair--track parts used off donor car

Keeping this short and specific.

Buy car1, car2, car3.

Car1 and Car2 are wrecked. Car3 is donor car. I paid $1500 for donor car.

Might use hood on car1, doors on car2 and other parts on other cars in future.

Would like to be able to track the purchase of this parts car and the use of parts off this car so I can see how much ive made off the parts car. Ive been using projects to track my builds. I have also followed a video to add a purchased car into WIP, along with expenses, created inventory item that then sell.

What im hoping to achieve: run P/L so i can easily see my current income and expenses. I use COGS to track purchase, parts and labor in their own accounts. I also have income accounts mirrored. This works for my purposes. If I use the inventory wip method, then I dont get a purchase expense on the P/L.

At this point I am entering checks for car parts/repairs, assigning expense accounts, setting as billable and assigning to project. Create invoice to sell car, add billable expense and then a line item for the vehicle sale itself using the difference from what I sold it for to the billable expense total.

I have also created a inhouse cash account. I have a inhouse vendor that I buy the used parts from, billable to project. Then I can transfer the balance from that cash account to a liability account for tracking purposes, keeping the cash balances clean. Not really a liability, but somewhere to dump the balance I can ignore.

These are all things i have experimented with. Recommendations on the right way or a better way? Maybe I am overthinking this and need to simple it back down. I like reports and seeing where my money comes and goes.