Nope, they were Arrow design built by S&S.I thought Nessie got Vekoma trains a few years ago, just didn't opt for vest restraints?
I honestly don't know the requirements for this but I think the bigger issue is that no one (that I'm aware of) makes a Arrow/Vekoma/Chance train that is lap bar only that is suitable for inversions so it would require an entirely new design. The only possibility is the RMC train that Chance has on Lightning Run which I'm honestly curious to see if they use the same train on the Hot Wheels coaster.Otherwise, since Anaconda's inversions aren't particularly high speed/forceful, I'm wondering if a lap bar retrofit into the existing trains would be acceptable? Or would that actually make it worse?
Either way, I think it's a much easier, and cheaper, for a park to just get the Vekoma since the Arrow Custom Looping and Vekoma MK1200 coasters are virtually identical. I also think it would keep the classic Arrow feel of the ride as well.