The converter is probably not helping the 60'.
4.56 is a lot of gear for the cam you have. What was the trap RPM? Did the front end drop when you let off on the big end? What rear tire diameter? I hope it's at least 27" or 28"
750 works better on my car after timing curve and AFR was dialed in.
Keep tuning what you have and once you are dialed in and consistent you can make educated changes to drop et.
Have fun with your car, I love my Post Sedan!
