right gonna build an efi cvh from parts i have spare

i have an efi xr3i

i simply wanna know if i can use the head from the xr3i engine on the bottom end of an rs turbo mfi item

are the any differences in the xr and rs heads or iare EFI heads all the same?????

i had herd somewhere that to convert to efi u can use xr2i parts e.g head and inlet