The SOHC head is different to the DOHC head, the blocks are the same, the only difference between the DOHC & the VR-4 version of it are the compression ratios (went from 9:1 to 8.5:1) and that was done using scolloped pistons.
And what about oil squirters under the pistons?
As I know in the case of 4G92 MIVEC it has additional oil squirters over the SOHC version, as does the 4G93T over the NA 4G93