depends on what pistons you are using and what head!.

4x4 pistons have a lower compression ratio than 2wd pistons, as the 4x4 head has smaller combustion chambers than a 2wd.
late spec 2wd head/4x4 head is better, early 2wd heads are fine but more prone to blowing head gaskets on exhaust side,.

Depends on how much power you intend to run though, as for manifold
the 2wd is designed for midrange to top end power,
where as the 4x4 is designed to keep lag low and increase low down torque.