In answer to your question above.

The dohc 8v was found in the sierra
The dohc 16v was in the rs2000 escorts

Both were known as the 14 lump.

The standard rs2000 was 150bhp the sierra was 125bhp.

You can use the same bottom ends but would need to change the head, loom, all the injection and most of the sensors, also the engine management, exhaust down pipe made

Has more potentiol than the 8v