camot

Sub made a carbureted Justy for a long time (late into the 90's) but the last ones sold by Subaru in the US were 1989 model year. The 1990s were FI. The last EA81s in the US were also 1989. I understand the EA81 carbureted Brat is still available in some places in the world.

You WILL overheat. The turbo rad will dump a whole lot more heat and believe me, the turbo puts out lots of heat. You will also notice that there is a coolant line to the turbo itself (that's why the turbo water pump is different) and if you overheat, it will cook the oil in the turbo and freeze the floating sleeve bearing that the turbo runs on. Not pretty.

Was the car originally a turbo? If not you need turbo injectors and a turbo ECU. It sounds like you are maxing out the injectors.

You didn't say what engine you have. The EA82 does use 11x1.25 head bolts. Threads don't pull out unless the block has been really hot. If so, replace the block. (I have a machine shop and do only Subaru's - trust me on this.)

It's on the driver's side. Personally, I'd pull the engine and tranny. There isn't a whole lot of room in the Justy engine bay. BTW, plan on spending at least 3 times as long as it took in a Brat.

Get a Haynes manual. Professional mechanics get in trouble with these things. For example, the two belts have to be installed with the timing marks 180 degrees out of phase. The timing marks for belts are not the same as timing marks for ignition. The job is not hard, it take me about 4 hours and I reseal the oil pump and replace the cam seals and O rings.