Your player will be super spoiled as they've already played the module.
According to the product page for White Plume Mountain Revised (3.5) on Dungeon Masters Guild:
The 3.5e version of "White Plume Mountain" is based closely on the original, with the design adjusted in some areas for balance and better polish. The three named weapons have also been statted up with the Weapons of Legacy (2005) system.
And, according to Tales from the Yawning Portal, the original White Plume Mountain has been
updated to the fifth edition rules.
Having compared both 3.5e and 5e versions side-by-side, all of the differences between the two are merely cosmetic or mechanical in nature. There are only two minor, legitimate differences between 3.5e and 5e:
The turnstile in 5e is a mimic in 3.5e (area 6), and the 3.5e map is shifted to force players to go through area 23 before going to area 26.
I like both of these 'changes', but they are cosmetic at best. The first is little more than a new wandering monster, and the second just determines in which order players enter rooms.