The most complex mechanical task I did before assembling my ERA was putting a new water pump on my old Camaro. I always did my own
oil changes, but that was it. I was concerned with my lack of experience so I went with ERA's bonded body option and didn't mess with body work or paint. The car went together nicely and I consider it to be a very well-built car, in spite of my lack of experience. There is a difference between lack of experience and lack of ability. If I were you, I'd focus more on your self-assessment of your capabilities. The skills you'll need to install the drivetrain, suspension, wiring, carpeting, etc. can all be learned and end with good results if you're handy and capable. So, in my opinion, lack of experience won't prevent you from assembling a nice car but lack of ability will, and only you can answer that.