I may be wrong but I believe the 1974 Plus 8s still had the 4 Speed Rover Gear box. Both of these adverts show it a 5 Speed. Perhaps both have had a gear box swap?? Or its a error on the advertisers part. I think the 5 Speed Rover box didn't come into the spec until 76 or so. Also, I think 190 BHP is a bit optimistic for a 3.5L. Realistically it is something less.
I had a Moss Box 71 Plus 8 and loved it. Light and agile and quick. Sold it because of the 4 Speed box, too busy at highway speed. Now have a 86 Plus 8, 5 Speed. Better on the highway but not as quick.
Cheers,
Mark
