Find a shop with a older caustic soda non epa friendly hot tank and let it eat the tubes out chemically or at least break them down enough for easy removal.
Also if it were me id get that block cleaned and get a good mopar guy or shop to look so far up it you can see the back of its teeth.
Who knows how hard of service life that block has had and who knows its real health, id check and see if the oil passages from the main to the cam have been drilled and others as well.
Many times when we used to tube we did drill passages as well.
Caustic dip or even just plain old lye eats aluminum, but doesn't do a whole lot on copper or JB Weld. Doesn't touch cast iron or steel. A gun drill might do the trick.
