As someone building a particularly stupid car in a genre almost but not entirely unlike the OP (a turbo LS1-swapped Rover P5), I am not totally making stuff up when I say that this:

> You have to be prepared to spend potentially years on it and huge amount of money, even on relatively simple projects.

is not at all mutually exclusive to this:

> Honestly, just learn it like anything else.

I didn't really know what I was doing when I started my project. I had an idea and the desire to make it happen. I barely knew how to use a MIG to do the fab work, so I got good (enough) at it. I knew nothing about LS engines, so I learned enough about them at each point I needed to know something about them. I only have a vague idea of how I'm going to do the next phase of it; I know that I can figure it out with enough thinking and by making all the mistakes I need to make. I don't know how to TIG, and it'll be really useful if I do, so I am learning how to TIG.

Start somewhere, and the more you do, the more you can do.