Are you sure those cam numbers are correct? Most big block cams have more exhaust duration than intake. Is it possibly 234 int, 242 ex. If so, you are getting close to reversion. Depending on your exact set up, it could happen. 7.5 lbs of fuel pressure is a little bit high for that carb. You might be pushing the needle off the seat and allowing excess fuel at idle. No need to use more than 6 lbs. Good luck.