It sounds like pinging. 180 is high for 91 with iron open chamber heads. You will want to be very careful tuning. Also, that Edelbrock is always lean from the factory. I'll put money you need to buy the strip kit for the carb and go up in jet and metering rod, and more than likely swap the springs under the power pistons. It's lean under full throttle. slow the timing curve down so it doesnt come in full until 3K, and drop the centrifical amount to 14-15° with initial at 18-20°. I think the 750 Edelbrock would be a better fit.