I had the stock front disc brakes also and the wilwoods were still 38lbs a side. Sounds like the car with the big block should be in the 3100-3200lb range. When you put on the glass hood did you removed the springs and arms? and the hood latch assembly? My car also has a back seat but just a standard one not the original foldown, i have a radio and two speakers in my car do you? if you do do ya need it?