blittle, I prefer the round tube frames, as I feel it looks cleaner and more professional. It will allow for a little bit lower riding car and more room for exhaust and mufflers. If you have access to a tube bender, they are no problem to make up and you can fit them were you want them.
Some guys still like or prefer the 2x3 box for some reason for street cars, they say it is stronger for the street, but I think it is because it looks more like the stock frame rails.
Last year I upgraded the frame on a vega for a guy, the frame was built in the 80s, square tube, 2x3 and had been added to with 2x2 square to the front with some weird suspension set up from a chevette, (you remember those??) It had worked well for the original owner for many years.
The guy took it to another chassis guy .. :shock: .. to replace the cage which would not pass cert to to wall thickness.
After the new cage was installed, he brought it to me to install struts on the weird 2x2 setup.
To make a long story short, we ended up replacing the complete old frame with a new round tube frame under the new cage. Kind of a backa**wards way of doing it , but it turned out ok.
The vega is now back in my shop for 4 link install, as it was originally a ladder bar car.
you can see pics of it on my website, its the red vega, I dont know how to post pics here.
good luck with the project....