I think the answer will lie in what you put behind the 235 (or 261). If you have a stock transmission and rear end, the 261 will give you more torque but for mixed town and highway driving I'm not sure the difference will be that great. Costly, yes. More noticeable the more weight you're dealing with I'd say. If you have a rear end with a ratio like 3.08, then yes...any extra bit of torque will be your buddy.
But you know in 1959 Chevrolet changed the cam in the 235 to improve torque output at lower rpm, yes? 217 at 2000 rpm as I recall. 261 of same date would have produced 235 at 2000 as I recall, so sort of pricey for the bit extra after the cost of rebuild.
