A ____ of ____ can be used two ways.
One is to make the A ___ the quantifier, simply telling you how many of the second ____ there are.
Many students are entering the museum
Several students are entering the museum.
A bunch of students are...
A busload of student are...
It only makes sense to use the plural form in that case. I would argue that "A massive amount of resources..." is being used that way.
The other way is when the A ____ is the subject of the sentence and the second ____ is simply telling you more about that noun.
A family of 12 is hard to feed.
A colony of red-tailed warblers is...
A village of people who had never contacted the outside world before was discovered.