The first stand I built was for my first 75. I used 2x6s, 2x4s, 4x4s... it was overkill. You could probably set a car on it without it failing.
I bought, a couple of years ago, a 180 and a commercially made stand. The commercially made stand surprised me in that it doesn't use huge pieces of wood as structural members. It does a very good job of distributing the weight across 1" thick members. I was concerned and spoke to my dad, who is a mechanical engineer, and his opinion is that it was just well designed for it's purpose.
Good luck with your stand.
Jim