67 plymouth barracuda fastback 273/727

I am definatley going to build it to suit me I'm just not sure what that is I know it will look original from the outside, i'm just not sure what to do with engine, Like i said I'm not going to race I'm just going to drive it when its nice and go fast when the law ain't lookin. I'm sure i can do that with a 273 but if i rebuild it do you have any suggestions for upgrades and I see a lot people talking about reinforcing the torsion bar sockets and putting in subframe connectors Whats neccasary to have a safe car