I haven't had much 1200 experience but I have had lots of 1000 experience
Front suspension is transverse leaf yes
Disc conversions are plenty but finding someone who has actually done it and remembers how and what was used is the hard part
I love my little 1000 coupes
Nice and light...handle like a go kart
and no strut towers in the way.

Oh yeah.......someone got 1000's in left hand drive....I have the manual on it

So both the 3.9 and 4.1 centres are LSD or do you have a 4.1 LSD and a spare 3.9 crown and pinion ?
Whats its series ?......H xxx
Is it leaf setup or coil ?
In good clean condition ?

was hoping to haggle on the A14 ones.......oh well

I am using 4AGE clutch on mine with a celica 5 speed

Oh by the way did I mention my flywheels ready to pick up........whoooooooppppppppeeeeee
It weighs in at just under 4kg apparently. Can't wait to get it here from Melbourne

more details of the "rally diff" please
flange to flange dimension ?
Disc or drum ?
$$ ?

did
hence the "well?"

well ?

I tried to get a Tilton one before but had no luck....well done to get one out of them.
My alloy one will be ready Tuesday.
$465 + GST.

Good luck
I have been playing with 1000's for 20 yrs and I haven't found anyone that knows anything about them
Virtually no-one knows about A series engines.
Thats why I've been trying to do everything myself.
Feel free to ask questions though........I might be able to help.

Ross piston in the U.S will make forgies for $389 US plus rings and pins to your specs.
I'm thinking about it if I can't find anything locally I like under $1000