Wow, what a wonderful gift! I have this edition: Paradise Lost (Penguin Classics) https://www.amazon.com/dp/0140424393/ref=cm_sw_r_awdo_BMR7H4JJF0D7G9QHEABP?psc=1
It's just over 500 pages, so I guess it is kind of hefty
Amazon and most book sellers have it since it’s a classic like Dante’s inferno and works by H.P love craft. paradise lost on Amazon it’s also relatively cheap.