What's a 6.4 worth??

I’m a novice at all this. Was thinking big block for a while because it’s my dad’s dart and that’s what he wanted to do, but he passed and I inherited this and am not trying to drag race it like he was. I think a 6.4 in a 3000lb car with AC, etc. will be more than enough for me. It’ll be a while before I can dig in but have been on the site almost daily reading up on stuff for 1.5 years.