most likely a 6N block. the 8V 1,6L block is slightly taller. The G40 block cant be bored and stroked to much more than 1520 cc with the long stroke Oettinger/Sorg crank, a bit less with the diesel 1W crank. With the Oettinger crank, you have problems getting the compression height on the pistons low enough for decent compression.
As for the head, you can either use a 6N head (for better flow) and an adapter for the PY/3F manifold or use the PY head