At an emotional crossroad

Sorry for your loss.
I did not have a very good relationship with my dad for many years. He was an abusive alcoholic, my mother divorced him when I was around 14, and he blamed her for everything possible. He always said that she turned all of the kids against him and constantly played the victim.
When I was young he was always buying and selling cars and trucks, doing engine work, body repair, whatever was needed. I am the youngest of the family and when I turned 16 things only got worse. I was something of a hellion and got into a bit of trouble with the law. Nothing serious, but I guess it was a great disappointment for him. I didn't see him much throughout my 20s, but did stay in contact. I got married in my early 30s and found a way to resolve all of the issues between us. I had owned a lot of fast cars as well as a few motorcycles over the years, which he did not approve of, always said I was wasting my time and money.
When I was building my 70 Dart, he started showing up at my house more often and took a real interest in the project. I found it a bit odd since he had always hated Dodge. It was a good way to spend time together doing something that we had at least a common interest in. He's been gone since 2006, I drove that Dart for many years, and to his funeral, sold it 10 years ago now.
I believe that you have to do what is right for you, but I also think that you have made a connection with your dad through that car. If you are not able to put a hemi in it, build it according to your budget and enjoy the memories it will bring you every time you get behind the wheel.