If you can afford that much a month for a project then have you considered maybe buying a finished car from a classic car dealer that finances? Just a thought. I certainly understand the want and desire to restore your own car. But 5 years is a long time and lot can happen in life, especially at your age. Working in a bodyshop is a huge plus though financially.

In the end write it all out on paper first. You can stick to a budget if you watch your spending, but its the little stuff that adds ups.