I took my battery to an auto store and had it tested and it was no good, I bought a bran new one with 900 cranking amps and 750 cold cranking amps. Still nothing when I turn the key.

I've been looking over my wiring schematics again and I have everything wired the way the directions say to. My battery has a big fat ground wire right to the frame with freshly ground metal under the contact. Same with the engine to the frame and body to the frame. The positive goes right to the big stud on the solonoid and to the MSD.
I figured my ground to the gauges has to be good because their internal lights work.
The starter isn't new or anything, but I assumed it was fine because it worked about two years ago which was the last time it was on an engine.
If I took the starter off to test it, should I just connect a positive right to it.
does the starter ground through the block? Is it possible that I don't have clean metal between the mating sides?