Putting money into the valiant, suggestions?

Hey guys i have a good buddy who bought his girlfriend a 71 four door valiant for her daily driver. It's in great shape it runs and drives great never skips a beat but they want to put some money into it and make it a dependable car. Not that it isn't dependable already but he wants it so that she can drive cross country with no worrys.

I told them to start with an engine rebuild, trany service, painless wiring harness, and a good once over.

one other thing can you guys point me in the right direction for a good place to buy interior parts?

oh its a slant six