The 60s Triumph 650s were faster than that later model one, and had about 50 hp in the case of my 1970 (twin carb models, anyway). My Bonneville is a bit faster top speed I think, but the R65 feels like it accelerates faster from a stop.
That's my hazy recollection, also. (All my recollections seem to be hazy, these days.)
During the 1966-68 period, I lusted for a Triumph and studied the sales literature. One of my fellow lieutenants in a Nike Herc defense in the Southern Ohio cornfields bought a Bonneville. I didn't think I could afford the Bonnie (it cost about $300 more, I think!), so I locked onto the concept of the Thunderbird, which at the time was one step down in the Triumph line.
I ended up not buying the Triumph (or any other bike, for that matter). I had been a teacher before being invited into the Army, and while I was in for my required two years, the teaching market fell apart on the East Coast. (Enter the "Baby Bust.") Rather than go back to starvation wages in the school system I'd been in, I extended my active duty with the notion that I was on my way to a frozen missile site in Korea. When I got orders for VN instead of Korea, I was pleased in a perverse way—at that time, guys were being shot at and (occasionally) killed in Korea, but were not receiving combat pay or any of the other perks(?) that US troops in Vietnam got. I figured, WTF, I'll be warm(er) (anyone who endured Monsoon in the northern part of RVN would appreciate that "er" parenthetical), and I'll make more money (tax-free for the first $500/mo.) So, away I went.
Upon return, I found that Triumph (or any other non-HD) dealers were scarce within 300 miles of El Paso, home of Fort Bliss. Then, the principle of "feces accidit" took over, and the idea of owning any kind of bike faded away. (Was going to get my private pilot ticket through the FB Flying Club, but got Germany orders before I do either do so, or resign.) Then marriage, unmarriage, remarriage, and relocation took a further toll. The dream faded. (Spouse #2 was survivor of an airline-pilot spouse, so flying was
verboten, and hated motorcycles (at least as long as a dependent child was in the equation), so my re-entry into riding was delayed for an extended time.
Confession time: My first acquaintance with the BMW motorcycle was not positive. When I was in college, one of my classmates, an absolutely wack-o Army brat, owned the first Airhead I'd ever seen. (From the period, I'm guessing it was a /2, though whether 500 or 600, I'm not certain.) I still have vivid memories of this kid trying, for an extended time, to stomp-start that Beemer. (Can't really call those step-down starters "kick starters.) It seemed to require at least 5 minutes to start, every time. Also, this kid was so off-the-wall, I'm certain that I transferred negative impressions of the person to his ride. (We never do this with the H-D crowd, right? (};O) ) Learning to love an Airhead came later for me. Once I did, I never looked back at Triumph.