351W ignition problem

Looking for a possible answer to a problem I am having with my 351W. The engine is in a 1986 full size Bronco with all emissions eliminated. The carb is an Edlebrock 600. Due to time constraints, I made the mistake of not building the engine myself. I purchased a remanufactured long block. Engine ran great for the first 1000 miles. Then began running very rich. I messed with the carb, ran a little better. The very next day the engine began "chugging". I replaced the carb with another edlebrock, and then a Holley. Engine will not even fire. During cranking the engine will hesitate every couple of seconds but will not start. I replaced every piece of ignition when I installed this engine. I have since brought #1 to TDC and set the ditributor to number to no avail. I even replaced each ignition piece one at a time with the old stuff that I know was working to make sure the coil, igntion box etc. were OK. The rockers all move, I have spark, but during cranking the first spark is bright followed by dimmer sparks on subsequent firing. I picked up antoher distributor to try later this week. Any ideas or suggestions are welcome.

Very perplexing. ????

If anyone is interested, I pulled the motor and low and behold no compression 5,6,7,8. Bad head gasket. For anyone in Michigan contemplating a long block; depending on how the engine builder takes care of the situation, I may be posting a buyer beware of the company.