Allow me guys.......

Welcome to the forum, and good choice of car!

I've got a couple of Supers, but have only briefly driven the Cloverleaf, as I bought one for parts, and only drove it round the block really.   The Super is a far superior car, and I wouldn't even think of buying a Cloverleaf. 

The most important differences are mechanical.  The Super has lower gearing than the Cloverleaf, something not to be underestimated.  The Cloverleaf was always criticised for having gearing far too high.  I can believe this as even the Super has fairly high gearing.  As an illustration, my standard Super is only just getting into fifth gear after the finish line at Phillip Island, at about 180km/h.  It is fairly good for normal street driving however.

The Super also got stiffer suspension.  Again this is still fairly soft for track work (search around this forum for a while and you'll see a few pics of mine on it's doorhandles), but is actually pretty good for road stuff.  It's very comfortable, and although it rolls a bit, it does hold on really well. and can give you a moderately sporting drive if required.

The Super has the same suspension settings as the 75 V6 I believe, and it also got the better clutch from that car. 

Other than that it's mainly cosmetic, although one important distinction is that the Super dropped the digital dash for the analogue one.  I gather the digital dash is a pain in the a**e.

I haven't heard of any injection/rev changes, but I'm no expert.

There are certainly far less Supers around, as the Cloverleaf gave the car a bad name, so they struggled to sell.   But they were a far better car, and rated by the Aussie media as a better all-round car than the 75 (2.5 V6).

There's a good website here http://www.geocities.com/MotorCity/Downs/7709/alfa90.html with some information and manuals on the 90.

There's also a beautiful Super for sale on ebay at the moment.  It's in NSW and it's not cheap, but I've seen the car and it looks almost like a new car.  Probably one of the best around.  No relation/friend of seller etc......

Good luck mate! Let us all know how your adventure goes.

Yeah, I'm with you Evan - "Dorothy Dixer" of the higest order......Yes, just who is the mysterious "Sullo"....

BTW, I did find the answer both interesting and informative and possibly may have changed my views on 90's somewhat....mission accomplished.....

My sincere apologies Sullo for hijacking your topic - it's a bit rude really!  Welcome to the forum and congratulations on having such fine taste to consider not only an Alfa Romeo but one of the  best appointed and undervalued models of Alfa produced.  If you're not already I hope you'll consider becoming a member of the Alfa club also.

I hope Sheldon's information is of use - I've looked up my copy of David Wright's Alfa Romeo Downunder.  It lists the details of the Alfa 90 and Alfa 90 Super together, suggesting that the engine outputs were the same:

Bore & Stroke: 88mm x 68.3mm (2492cc)
Induction: Bosch L-JETRONIC fuel injection
Power Output (DIN): 117kW (156 bhp) @ 5600rpm

These details are listed  for the 1985-86 models of 90 and 90 Super, and then repeated for the 1986-87 models with the only difference being the chassis code and body code, and that the engine was for unleaded fuel.  Unusual that the book shows identical power output for unleaded?

Not sure this helps, but it's all I've got...

cheers,
Evan.

The most important differences are mechanical in the clucth/transmission as mentioned.
The temperamental twin-plate clucth was changed to a better single-plate.  The original (same as GTV6) gear ratios coupled to a 3.5:1 diff ratio gave the first 90 rather awkwardly tall gearing. This was replaced with the same as 75's with a 4.1: diff, in the Super.  No LSD though. 
The styling was also radically enhanced with the Super..........with a firm but accurate blow just above the left temple..........   

Not quite sure what you mean there?  Hard to get as spare part?  maybe.  Check out mine in operation in pics attached. BTW this one has been crashed so the shutlines and colour matching is usually a bit better than on this one!

You shouldn't find any rust on a 90, they were galvanised from new.  In the three I've owned I've only found a tiny bit of superficial rust on a quarter panel.  Buying guide here:-  http://www.geocities.com/MotorCity/Downs/7709/buying.html  Suggests checking rear wheelarch and bottom of doors

Air-con is not up to much on the 90.  It might cope with temperature in the early 30s, but good luck with anything over that.

Make sure headlights are in good condition, they're very hard to find, and pretty expensive.  I bought my parts car (with good headlights and briefcase) for half what I was quoted for a pair of headlights!

That is all for now.  Good luck