I would go with whichever one you can find. Either one is like hen’s teeth, so good luck. I pair my 901 with my colt competition upper.
There is a 6944 that is already pinned that is selling on Gunbroker for a decent price. Looks new and comes in the box. There is also a used 6940 that is here in Texas that is up for sale. I guess they weren’t quite like hen’s teeth, but pretty close.