Farmall Cub

My new rebuild of my 58 cub has water (antifreeze) leaking a little around at the block to head surface. It also has
water leaking out of the intake manifold. I took the manifold off and water is leaking out of the 3/4 manifold intake port.
Removed the head and all looks fine that I can see. Is this a crack in the block at the valve? Has anybody seen this problem? This was a basket case that I put together. Bored 30 with all new valves and guides.

Also checked the head and it is very flat. I have a pro straight edge and no warpage.

I used heat to warm up a suspected crack area and it worked, when it got hot it expanded enough to find the crack

Head removed. Dry the valve seat area and top of block. Add water to the engine block/radiator to about 1/16" below the top of the block.

Since the leak shows up with a cold engine, the "crack" area should show up as a damp spot.

Another thought. Head bolt threads in block tapped/cleaned?

All headbolt threads were cleaned and sealer used on threads. I will try the water test when I take the head back off.
Thanks

Well, I hope you do not have any cracks!

And it was just a defective head gasket!