M13 will be not economical and when it come to Khyber but of course, when you have already it in spare so you can utilize that one.
Alterations would be required..Btw if you want you can trade-in that engine and Khyber original engine in lieu of 2sz-fe with good compression ratio readings.
If you have emotional attachment with m13 then during installation in Khyber, you can also change only gear to Automatic transmission while retaining your old M13 Engine.
If you are in Karachi, then Usama Automobiles is ideal name for your swap job