timing problem with 8051 integration

I though of a "work around" solution: if after I compile my 8051 on it's own, i save the file, and then integrate the post synthesis 8051 with my SPI, it might overcome the problem.

Can anyone explain to me how do i do such a thing? I mean what file from the 8051 project should I take and add to the combined project (instead of the 8051.v files I added as for now), and how do i tell the Quartus to keep it's design?

i am still very happy to hear other ideas.

Tahnks again,

David