Ticking Noise - 273

I did some running around in my 66 Barracuda today, and after I got home I drove it up on ramps so that I could check out underneath. I let it cool in the driveway while working on some other things. After it cooled down (approx. an hour) and I checked out underneath, I fired it up to drive off of the ramps and it is now it making what sounds like a lifter tick.

The car is bone stock 273 hi po, with solid lifters. Thinking it could possibly be a sticking valve I tried carburator cleaner on it (spray in carb til quits, and then let sit for 10 mins or so), no help.

I pulled the valve cover off of the side that the noise seems most prominent (passenger side) and the rockers and push rods seem ok.

Any ideas as to what this could be would be much appreciated.

Thanks, Rob