Yasir Sb.,
In my experience, taking short cuts often become long cuts. If Honda used a gasket in this place then you should not deviate from using a gasket too. Using just a sealant is not advisable. Making gaskets yourself is no rocket science. All you need is a good pair of small scissors and a bit of oil/petrol/water resistant paper of the correct thickness. Apply a thin layer of oil on the mating face, press this oily face to the gasket material and you will get the required profile imprint on the paper gasket, just cut along the imprint and within 5min you will have a gasket. Getting oil leaks later is not worth saving this small inconvenience.
BTW engine is looking awsome!!