look most readers would just past this question by, but I'll try to help you out a bit.

the only way to not change the head from a SOHC to a DOHC is to do a complete swapp.

but the easiest way is to change the head only from the SOHC to a DOHC.

the only problem I have is that I dont know if doing the head swap would work.

hope this helps.