I fired up my new engine over New Years Break. It's an 1971 460 with DOVE-C heads. I bought the long block rebuilt from a major engine rebuilder with a great reputation. I then put my peripheral stuff on including A Mallory Unitlite distributor with a Mallory internal resister coil and an inline surge suppressor.
I followed the directions for installing the Distributor from both Mallory and my engine rebuild book. The distributor dropped in at TDC on compression stroke for the number 1 cylinder. I then wired the ignition circuit with my American Autowire kit, and fired up the engine. It started first time. I timed it by ear and proceeded with cam break in , per warranty info provided by long block manufacturer. I should also note the timing chain was aligned properly between the cam and the crank by manufacturer before I put the timing chain cover on I checked this.

So with the above info
I then connected the timing light to the number one cylinder wire, and checked my timing settings. The timing was showing 50 degrees before top dead center, and running fine. Not sure what may be the problem. The timing light is relatively new(a few years old) and everything sounds and runs fine.
The only thing I can think of is I left my wires long until I can get some wire looms to properly trim them to length. They were overlapping the number 1 wire during the timing. I haven't retried the timing since my gas tank had a leak from one of my connectors that needed to be tightened and sealed, so next time I get out to the shop, I'll be able to refire it up again and recheck the timing.
In the mean time has anyone ever experienced this? Any ideas as to what could be wrong, i.e. wires off by one one the distributor cap?