Trouble starting

In the process of trying to fire up my 5.7 with 6spd man with a hotwire harness.

I have wired in the pushbutton to eliminate the issues with the igntion switch. So I have 12+V supplied to the pink wire from one of the ignition points, and also ran a wire from the ignition to a pushbutton and the yellow wire on the other side of this as told to.

I originally had no response at all until I realised the clutch safety ground wasn't connected, so I grounded that and now it has some response but doesn't fire. It almost sounds like it's cutting in and out, I hear the starter motor do a quick tap and the throttle body makes a little sound but it's almost like the power is cutting in and out.

If you hold the start button in, it makes a sound like TAP TAP TAP TAP TAP like the starter motor pinion is extending then losing power, extending then losing power. I have a video which I will try and reduce in size to upload.

Any tips or help would be great. I just want to hear it pur!