SOOO many questions

I have a 68 notchback Barracuda. The left torsion bar has twisted out at the torsion cross member due to rust and it's former life as a drag car. I plan on reviving it for my driving pleasure. I will be rebuilding a 360 I have to have somewhere between 350 & 400 HP. It will be a manual transmission car 4 or 5 sp yet to be determined. I have a spool mouth k-member from a 73 Dart sport as the engine was out of a newer Chrysler and it has the spool mounts and the sway bar is tucked in nicely on that k-frame. I have a replacement torsion member ready to install that is in great shape and was carefully removed. I plan on taking the car to a shop that does Mopar frame work as the extent of work required and the possibility of screwing it up are not an option. The car is for "Sunday goto meetings" type of driving. It would be more likely to find me doing auto-X than drags. Having said all that! Now the questions:
To strengthening the chassis I plan on frame ties. Should I plan on torque boxes as well?
The flood pan will probably be replace as well due to the rust. Should I get a one piece or get the multiple ones?
I assume the torsion bars will need replacing. Any suggestions on what ones might be worth looking into? Ride height will be lower than stock but not slammed.
Should a rear sway bar be added? Diameter?
Any suggestions???