I reluctantly reinstalled the 1960 261 into my 1954 Suburban after its 235's oil pressure was about zero (three years ago). The 261 was in my shop and had been rebuilt by me in 1972. My reluctance to put the 261 back into the 261 was because I had wanted the Suburban to have original-style appearance.
I quickly got over my reluctance. The difference in power is (subjectively) noticeable at all speeds (I had forgotten the feeling, even though the ride in SWEET's truck had been impressive and had brought back good memories). The 261 accelerates faster from start and it accelerates far better than the 235 when cruising (if you need to pass someone; or, if you want to show off).
I have dual Carter-Webers now (which were recommended to me but I do not recommend them). I like SWEET's dual carbs better and I liked dual 261 Rochesters very much (they are now on a friend's/neighbor's 261, which accelerate faster than mine).
Back in the early 70's when I rebuilt and first used the 261 in my Suburban, I used the original single Rochester carburetor (the 261's original carburetor). The increased power of the 261 over the 235 was remarkable, even with that single-carb set-up. I could cruise or accelerate on Interstate 64, going up Afton Mountain in the Blue Ridge Mountains - there was no way that my 235 could pull that mountain without loosing speed. There was no need, with the 261, to use the truck climbing lane.
