Using a different op-amp model for the project
The MCP602 and the UA741 are vastly different.


The MCP602 is rated for rail to rail operation.  The 741 isn't 
The MCP602 is a low power device.  The 741 isn't.  The difference is from hundreds of microamps of supply current (MCP602) to tens of milliamperes (741.)
The MCP602 operates on a single supply of 2.6 to 6 volts.  The 741 is normally described as a dual supply opamp operating on +-12V - though it will, in fact, operate on a single supply down to maybe 7V.  Depending which particular 741 you got (and what kind of mood it is in.)


Those are off the top of my head.  So, no, the 741 is not a good replacement for an MCP602. 

What opamp would be a good replacement depends on the actual circuit - and what you can readily get.  The MCP602 is not by any means a rare part.  That you can't get one makes it likely you would have trouble finding any substitute that anyone here could name.



There also many reasons not to use the 741 (or the 1458 dual version.)