Due to a good leak in my 20g

I will be setting up a 33g (at least a 33g footprint) my PC is not going to cut it so I am going to build a MH I thinking of a single 250w .........BUT I don't know what parts I need

I will probably get everything from Bartle & Gibson. I know the cords that I need I have done that before on my 400w. I think I need like a M58 ballast? and mogul socket?.......little help please
Maybe this should be in the DYI........maybe a mod could move please