I have a 73 duster drag car with a caltrac rear set up with springs, shocks and the front shocks.
I used to have a 500 HP engine and it would always hook and 60 ft well.
Now I have a 436 HP engine in it and it only hooks once in awhile.
I took out the rear springs and checked the bushings for bind and there wasn't any. What I did notice was that the rear housing doesn't sit flat on the springs. The right perch is up in the front and the left perch is up in the rear.
Do you guys think this will cause traction problems?

When you bolt it down to the springs, it certainly seems that it would throw the spring rates out of whack a bit. However, My guess is that the traction issues you're having lie elsewhere. Even though you're down 64 peak HP, you could very well be making more torque lower in the RPM range, making traction tougher to find.

Absolutely it will Jack the car up and put it on jackstands so you can remove the wheels and measure the front toe in and then the back toe out, if it is more than 1/8 inch difference front to back you have a bent housing I use two carpenter squares or any two true straight edges and a measuring tape to measure 15 inches out from the center of the axles on the front towards the front of the car and then staright back, you should also try and do the same measurement straight up and then down the same distances from the center of the axles to see if it is bowed up and down also Let us know what you find, HP can and will make the 60 ft change also as well as tire age and track prep

I have looked at the Dyno sheets and think the difference might be 5 to 10 ft better but when it hooks the 60 ft is off by .08.
I'll have to check the toe on the rear. I was just thinking about fighting the springs.

I looked closer at the spring perches and they are crushed at the right rear and left front. Looks like I have to get some strengthened ones as well as a back brace.

You might want to add a new/another housing also. Trying to fix a bent housing is a waste of money.