carb suggestions

If you are going to a 3.55 leave the carb as is for now and see what the car does. 60' and trap rpm will change a lot. IMO Carb sizing is all about matching the combo and intended use.
I run a Demon 650DP and currently tuning a 750DP on my Magnum 360. So far top end increased 2 mph. I'm playing with pump shot to get the thing to 60' like the 650.