Personally if you really want a Nikkormat then I'd go for the FT3. They are all pretty indistructable however the auto AI is handy. The only thing I've had with a couple was slow mirrors but I've had an F2 like that so it's just an age thing. A quick service and it's good to go for another 30 years.
I gave up on them after I got F and F2's as the viewfinder was too dim in comparison. They are an ideal budget film camera for someone who still wants to shoot film and not worry about dropping, forgeting or getting their camera stolen. I've bought a few for less than 50 euro. Cheapest I bought was an FT2 with a K 50 for 15! It worked superbly.