Had the same problem before on my astra gsi and I had the lead order completely wrong.
Try swapping the middle two leads and try again,see if it makes any difference.
Try pulling the airfilter out and spraying some lynx deodorant into the airbox then try starting it,that was the only way that my motorbike would start,it spluttered like mad,but eventually kicked into life.
It'll be something very minor on that.
One thing while I remember,if you've had the engine stripped for a while,do a quick compression test on it.
In my old Rs I had no compression on a known good bottom end,tried everything to improve it,just couldn't work it out.
A quick squirt of oil down each bore and it fired up straight away.
We did a compression test again after running it up and it was spot on.
I believe that engines still going today in some way or another from what I've been told so it was a good un.