So whats the cost of a second hand engine compared to all the goodies hanging off a pre-built car? I'll tell you, it's a lot of time and money. Unless as stated you were looking to get your hands dirty + know some people who can help with stuff (cheap parts, cheap tuning, etc).
Look either way, TAKE YOUR TIME and at least get it checked over by a mechanic you trust who knows these types of cars or at least RAA, etc with compression test and anything else they can check.
GL