I have one in my 61 Pioneer. If I knew then what I know now I would've used 440 block. You are way limited to piston choices. Punching out to 426 is not always feasible, you will need to have cylinder walls checked for thickness to see if you have the meat to do it. Too thin and you overheat. If your intent is to build a run of the mill grocery getter, then build the 413 with the low compression cast pistons. They are readilly available. Anything other than that will require you have pistons made (what I did). 440's are common and available, they have larger cube from the getgo and the pistons come in all shapes and sizes, so to speak.