Reply to "Leak >>> Gaskets ?"

Frederic,
I took a close look at your #2 photo, with the circles and arrows, I see two things:

#1 - very important - the sight plug of your carb secondary float bowl has come out. It is lying on the intake manifold / head, below the bracket of the dip stick. Maybe you took it out, or maybe it fell out. You must put it in place before running the engine again - that is a serious risk of fire.

#2 - to the right of the oil pressure sender, I see a gap between the intake valley pan (turkey pan) and the end seal. A red arrow points to it. I think this is the leak of oil around the sender.

When an engine is rebuilt, it is common to mill the head and / or block surface; for flatness or to raise compression. When this is done, the intake surface of the head (or manifold) must be milled also, or the manifold will not fit. It is usually the head that is milled, so an "out of the box" manifold will fit.

It is possible this was not done on your engine. If true, there may a gap at the front. Look there for a possible oil leak.

Good luck, Rodney