That'll give you a totally different drink. Chartreuse and absinthe both have strong but different flavors; not to mention that a bijou has 3/4oz of chartreuse but that much absinthe would totally overpower any other ingredient.
Chartreuse doesn't really have any good substitutes that I can think of, it's got a very distinct flavour that's nothing like absinthe (I like to lovingly describe it as lawn steeped in everclear).
Still make the drink with absinthe and see how it goes though - it'll taste totally different but it might still be good, and the ABV and (lack of) sweetness of chartreuse and absinthe are at least fairly close.
In my opinion, Genepy is a decent substitute for Yellow Chartreuse, not so much for Green. Green has a very herbal flavor where yellow tends to be more floral.
in the best case you'll invent a new drink but I doubt it'll be very good; start with a very small amount instead of using the same proportions as with chartreuse and you may get somewhere interesting, like a gin sazerac kind of drink