No... The GP has a completely different body than the LeMans, though they're on basically the same chassis, the GP is just stretched a tad.
What you might be able to do, is do some precise measuring and put a shaker on a GP after cutting the hood... use a spacer if the shaker is too low or cut it slightly if it is too high... Then someone that is good with fibreglass can construct a similar spoiler to fit.
A GP isn't exactly my first choice for a Can Am clone.. But they are severely underrated.