car wont start

the engine was built years ago, and stored with lotsa marvel mystery oil. put it in the car last year as I was doing work on it, I put break in oil and ran it, it was getting low vacumn 10" I noticed a anti freeze leak coming out the front corner of the left cylinder ( front). the person who built the engine didn't put sealant on the head bolts. I pulled the heads, installed new head gaskets and new arp bolts. while I had the heads off I noticed all the valves on the heads carbon on them except the valves on number 1 cylinder they were spotless. I put everything together and torqued to specs, I then started the car to these problems

They were clean because they got steam cleaned by coolant, and may very well have trashed the cylinder, rings or valves from lack of lube.
Have you compression tested that cylinder yet?
It's also possible the coolant stuck the valve open.