That gives you time to execute 80 instructions. My answer is no.
I should be more clear -- 80 single byte instructions...
access 40 integers or whatever..
The time is a bit short.
The Mega is a 16MHz Clock. So the period and the available time give you the maximum number of instructions you could execute -- or the memory fetches.
The newer ATMEL 8 bit processors with a 32MHz clock -- maybe.
The ARM (32 Bit) versions of ATMEL with 32MHZ clock and up -- maybe. It depends on the code and you did not provide any or an algorithm -- so it is just a best guess.
I would love to see the Arduino style of software on the 300-800MHz embedded systems -- for projects like yours and mine I would happily pay the $200 to $500 these systems cost. It would be a deal for really fast turnaround on the project in terms of bread boarding and testing. I would buy one today...