... 1zz1o snoop nizzle
The 2 official modules for NEXT
from just before the 5e release,
have the 3e + 4e + Next monsters
stats all together. iirc
this was a wotc online pdf, free too.
(not the adventure module itself)
So the conversion from Next to 5e
might be about as simple as it'd get.
I swear we discussed them around
here somewhere, including links,
but my google-fu rolled a nat 1.