need help with stock setting for oval shape and mesh input

[Anonymous]

https://a360.co/2IyCVk3     How do I tell fusion my stock is an oval shape and fit this design to it.  Problem being it is a mesh and too big to brep.  If I tell the software it is just box  it has many rapid tool crashes.. I posted the work peice.

[Anonymous]

Thank you for taking time to do this. Very gracious.