Bart,
The 1955 second series Chevrolet truck, the Task Force series, is a completely new body style. Mechanically, if you had a 235/261, the mechanics would be similar to 1955-1st Advance Design truck. Electrically, it would be 12v; the 55-1st and earlier were 6v.
I am less than ignorant about the 265 or any "small block" Chevy V-8 motor.
I bet that reasons for swapping in any later small block could be argued, base on each later motor being an incremental improvement.
In my simple world, the irrefutable value of the 1955 265 is that it is THE first "small block" V-8.
