Although there are no required maneuvers for a FR, I'd have to think really hard as to whether I could conduct a worthwhile FR while keeping the engine at 75%, or whatever the break-in instructions are. And I suspect I'd decide that no, I couldn't.
Sure you could do some navigation exercises, and steep turns, some hood work. And I suppose one landing, since you do have to land once anyway. But no engine failure scenarios, slow flight or stalls, multiple crosswind landings, emergency descents, most instrument work, go arounds, etc. I think it would be a pretty limited FR, and therefore probably not meet a reasonable standard.