hey mate thats coming on real good, work manships looks good too.
that wiring is a mess rip it all out lol.
not trying to be critercal, bit the roof bar as it is will gain no real srength as a complete cage a single diaginal or double (cross), is best and the norm, same with floor bars, will just tie all the structure in together properly.
cage bendding, notching and and workmanship looks really good though mate, nice one.
with the quality of it all you may as well build a full tube chassis , and get it tagable you know youll get bitten by the bug of racin