I smoked a hog head a few weeks ago it turned out great. The Tongue was still in it and it was good but could have been better with some more moisture. I would brine the tongue then slowly smoke it, allowing some of the fat to break down.
As to the heart, Personally I believe heart is best sliced or diced small. Seasoned it simply salt, pepper, oil (fresh garlic if you like it). Skewered then seared medium-rare over hot coals. Liver is fantastic this way also. My sons girlfriend ate nearly half a deer heart without knowing what she was eating. For years we had made deer heart and liver on the stove top in a skillet. I learned this technique watching Andrew Zimmer on bizarre foods.