My son and I are also building a 71 Valiant 4 door. His was originally a 318 A/C car, we're swapping a 360 in and beefing up the suspension. Don't worry about having a 4 door, there are a few of us here with them. Your friends will like getting in and out of the back seat easier with the back doors... They are made to be shared with more people.... :D
Don't rush it, it takes time to get it done. Here are some pictures of our car along it's journey. We are not done with it, but making slow progress...