I have ran the 268xe in my 440 for 2 years. Love it. Great driveability, slightly lopey idle and like Transman said, nail the throttle, and it cooks the tires.
I am installing the freshly built 440 I have been working on for my swb D150 and it also has a 268xe. Stock converter works well, as do power brakes.
I've had other cams in 440s in a truck, but hands down I like the 268 best.
I too installed it straight up.

84 D150 440/727
79 /6 swb D150
1964 A100 window van. Just because it has spark plug tubes doesn't mean it's a Hemi.



If ya haven't been there, ya just wouldn't understand.