Ok -so it seemed to be a combination of low fluid (forgot to account for the new trans cooler) and the linkage out of adjustment (didn't swap to the new shifter arm when the B and M floor shift got installed - silly mistake).
Car now starts in neutral and park and shifts through all of the gears.
Still don't have connectivity between the outer posts on the neutral safety switch in reverse - what sort of resistance should I be looking for? The center post to case is less than 10ohms in park and neutral so I figure it should be similar for the two outer posts??
Thanks for all your help guys.
Bryan.