Hey Mick! Nice meeting you too. Love the story about the wheels in the living room. My bedroom has a hood, bumper, and fender (my car is down for A/C) in it. My wife has begun the nag routine, so I've only got a week or so to get them back on the car!
No doubt you can get deals on parts that might not be there if you followed a "just-in-time" approach.
My argument is that the savings on that gets overwhelmed by all the parts you buy that you never use.
Plus, even if you do eventually use them, you have to store them and be able to find them when the time comes.
Storage of parts costs money and productivity.
And finally, stockpiling parts reduces your liquidity: you've got car cash tied up in parts that you can't use yet, and maybe even keeps you from being able to afford parts you can install.
The other side of the coin is that a JIT strategy requires decent planning skills and patience. Otherwise you'll always be paying overnight fees to make progress.
jp