You need about 2x the amount of boyz.
I'd run as many basic boyz as you can realistically afford, 2x20 + 4 trukks or 4x20 + 2 trukks is an excellent base.
Run a mix of shootas and sluggas if you like, I prefer shootas because I enjoy rolling nine BILLION dice. It seems silly, but there it is.
Add in your style of play (shooting or assault) and ensure you can handle mech lists in one way or another, and you'll have a fine ork army in no time.