?? Mystery Block Ports

So I am adding a 225 V6 odd fire to my 65 CJ. Since it did not come with that option that year, its a lot of conversion work. The engine is rebuilt and ready to stab, but I am still scratching my head on some holes in the block. I just dont know what they are for, and do not know the original application for this particular block. I am guessing most just need plugged but I dont know. Thank you for the help!
#1 Threaded hole just above exhaust port on the head. 1 near each exhaust port. Not the bolt holes for manifold.
#2 Two holes on passenger side of block near freeze plugs
#3 Hole on drivers side of block near freeze plugs

11/10 - Added better picture of #3. Its just to the right of the dipstick hole on the drivers side

 

# 1 looks like air injection ports in the head for emissions. You can plug them off. # 3 looks like probably hole for dipstick tube.

#2 to the right maybe oil pressure sender/gauge port but hard to tell from my phone.

 

Thank you nickmil. I did add a better picture of the mystery hole for question #3. Its just to the right of the dipstick on the drivers side...Appreciate your help

 

#3 it's a block drain hole . a pipe plug goes there

 

Thank you Ron. I really appreciate the resources on here to help answer questions. PRICELESS!