Most of the differnce between Tridents and Rocket IIIs is seen in the forward cant of the cylinders. In 1975, Triumph used these same blocks to make room for congress-mandated electric starters. That was the year of the death of British iron's uniqueness: They made them move the shifter to the left side, brake to the right, etc.
Mine's the only bike I've ever owned, and I'm hesitant to mount an American or Japanese bike, afraid I'll get into a stress situation and instinctively hit the shifter, trying to stop.
I love those old Brit Iron bikes, but I just don't think I could adjust to the shifter/brake switch.
Like you I'd be afraid I'd try to brake and hit the shifter instead. So I'm looking for either a new Bonnie or possibly a post-75 one at the moment.