One heck of... Could you rephrase the sentence?
"I'm going to write a book," Harkness said pleasantly. "When this is all over, I'm going to write a book."
Garraty grinned. "If you win, you're going to write a book, you mean."
Harkness shrugged. "Yes, I suppose. But look at this: a book about the Long Walk from insider's point of view could make me a rich man."
McVries burst out laughing. "If you win, you won't need a book to make you a rich man, will you?"
Harkness frowned. "Well... I suppose not. But it would still make one heck of an interesting book, I think."

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It means a good book. Sometimes it can be taken as saying "the best." Heck is a censored way of saying hell. He could have said, "It would be a hell of a book." Which means the same thing, but "heck" is a toner / nicer way of saying it.

For example if My friends and I go to the beach and i plan on it being fun, I would say, we will have a heck/hell of a time at the beach.

Heck or Hell can be used, but don't say hell to people you don't know lol. So we say "Heck". (Very common) Hope this helps

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Я бы перевела как.. "Ну.. я полагаю, что нет. Но подозреваю, это сделало бы книгу чертовски интересной."

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"Heck" is a softer version of "hell". In this case, it means "it would still make a very interesting book".