A stunt puzzle! What TH?? Each square with a circle in it could be filled with an H[eads] or a T[ails] based on COIN FLIPS without, so the revealer claims, affecting any of the clue/answer pairs. For example, the clue for 31A/D is "Breaking records, maybe" and the answer could be either HIP/HOP or TIP/TOP. I especially liked TINT/HINT for "Slight coloring" (6D). That one was paired with the more sedate STOCK or SHOCK value. The pair at 1A/1D deserves mention for the entertaining clue: "Something at the end of the hook?" FISH/FIST. HAHA! BASHES/BASTES at 56A is nice for its non-rhymingness. And HEATRAY/TEATRAY is notable for its change in word boundary. I liked the theme ALOT.
I don't think the rest of the fill was afflicted by the ILLS sometimes associated with a stunt puzzle. I liked KITED, ASTUTE, LAGGARD, SHEAF, STABILE, SLATE, KEVLAR, and SLIVERS.
The answer NYE for "Dec. 31" took me a minute because I went the easy route with crossword darling evE at first. 5D: "Place for a mogul" (SKISLOPE) is fun. And I thought 67A: "Falling down in a pillow fight" (EIDER) was ducky. :)
Overall, an excellent Htursday puzzle!