New Duster owner from Cali ...hi there

Just picked up a 70 Duster with 72 340 in it. MAJOR project but been wanting one of these for a while. Its been a while since I've attempted anything like this, so I will be on here ALOT looking for advice and ideas. 1st decision is whether to build the 340, or do what my heart tells me and squeeze a 440 in it?? It's a factory 318 car. Should be fun!!