47-55.1 Chevy 261 inline six - chasing coolant leak

[TX3100Guy]

Some of you may have seen my thread regarding moving the draft tube, at this point I am reinstalling my re-built (for the second time) 1959 261 Chevy inline six engine (read the thread if you want the gory details)

Now I have re-installed the engine, rebuilt the Stromberg two-barrel carb and have the engine timed and running nicely. However, I have a coolant leak that is bugging the hell out of me. When I first saw the leak, I pulled the radiator and used a black light flashlight and could only find coolant sitting in the bottom edge of the timing cover (front engine mount). I checked all the bolt tightness around the water pump and the timing cover and found one slightly loose bolt for the water pump, but the flashlight showed no traces of coolant coming from that area.

Hoping I had found it, I put the radiator back in and let it sit with coolant in it for several days and there was no leak. I just fired the engine back up, ran it for 15 minutes, got it up to temp and found a leak at the exact same spot at the base of the front timing cover.

My question is this, is there really a water jacket area near the front timing cover that could possibly be leaking? When I initially had the engine out a year ago and tore it down to a massive oil leak, it was coming from a cracked front main cap on the crank. With the timing cover off back then, I don't recall any water jacket access. Where could this coolant leak be coming from?