sorry to say, but cams going flat tend to eat engine bearings. you should check the bearings and crank.
if they are bad, then install a 4.000, 4.250 or 4.500 stroke crank for more cid and more torque. would need to change pistons.
headers help the mid range torque a lot!!
266 crane or a comp XE262 will be about the same. furthermore, if the crane cam went flat then the XE compcam will most likely go flat sooner due to a more aggressive lift rate.
make sure to use zddp oil additive during break-in and at every oil change. cost 10.00 extra at each oil change. todays engine oils suck.
could also try a BBC over cam oiler. They worked on my BBC's.
could also try grooving the lifter bore.