I realise I am coming to this discussion somewhat late... but I reckon I can shed some "complete" light on what you've rebuilt.
The ONLY Scott Pro Racing to feature Columbus MaxOR tubing was indeed the 1991 model and it was, as the catalogue shows, produced in Green/White with a "black chrome" finish spinner fork. I know, because I had one
30 or so were brought into the UK by the then Scott distributor Moore Large in a variety of sizes and *most* were sold to shop staff on a special deal for "racing" purposes via a loose "shop team" arrangement. Shops were given the option of running either a Diamondback or Scott team. The shop where I worked decided to run a Scott team. Two of our guys selected aluminium framed XT equipped bikes, one "Pro Evolution" which was raised chainstay frame in blue green and white, the second a pro America which was a standard diamond frame in red blue and white. The other two of us selected the Pro Racing.
As it happens, the reason I've stumbled on this thread is that whilst I was racing as part of that team, I was snapped by a random bike press photographer at an even near Leeds and the image appeared on the front cover of the first issue of "MTB Monthly". I'd lost my copy of the mag years ago in a house move, but it suddenly appeared on facebook!
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So... what have you got?
Here's what I know...
About 11 months after I took delivery of my pro racing, it developed a hairline black line (akin to a crack) around the union of the downtube and headtube. My team-mate's frame, upon inspection, had exactly the same apparent crack. It followed the weldline. We contacted the distributor and they immediately sent us replacement frames... but were warned in advance that a pro racing frame was not possible... we would be receiving a black frame with neon yellow decals, but otherwise identical... Max OR, lugless, ritchey drop outs, brake noodle, double bottle mounts... and that it was referred to by Scott as a "Pro Only". In reality, I believe Scott had a higher than anticipated rate of headtube cracks and that a replacement batch was made with beefed up welding around the risky joint. The speed with which our frames were replaced, without *any* quibble implies that Scott had prepared for the eventuality. The "Pro Only" was NOT a model that could be bought off peg and nor was the frame an item made available as a standalone.
Here's the bike (I still own it) in its current guise... 25 years later. It had a number of "upgrades" carried out in the early 90's to the point that aside from the XT rear mech and 7 speed thumbies there is nothing left "original"
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Incidentally, I had a set of Scott Pederson brakes on the back of mine, but they were NOT original equipment, I bought them as an upgrade and they were brilliant, kitted with KoolStop Eagle Claws. The original pro racing was XT throughout.