I've read through these reponses and will now give mine.
The Remington 600 was originally conceived as a bolt action saddle gun. The action was based on the 700 but modified in several ways to make the rifle as short as possible.
The tang and the receiver bridge were shortened. The rear screw location was moved as far forward as possible. The trigger finger lever was located at the front of the trigger housing. These changes allowed the entire barreled action to be moved brearward in the stock by nearly an inch. Because of this rearward location, the bolt handle was dog legged forward to keep the knob from hitting the shooter's trigger finger on recoil. At the same time, the handle was flattened and kept close to the stock. The point of this was to allow the rifle to fit well into a scabbard. The bolt stop, disliked by some, was made the way it was so the bolt stop would not be depressed by accident during rough use. It's not a problem to use and does it's job.
The 600's stock was, in a word, homely. The rear end was ok with a decently shaped Monte Carlo comb but the squared and too long forend wasn't that great. Nonetheless, it made an acceptable handle.
The nylon trigger guard and floorplate saved weight and were quite durable. Durable or not, plastic is hard to like and not many really like the 600 guard. Another plastic touch was the plastic ventilated rib affixed to the 600's barrel. The only reason this was added was because some one felt it looked "cool". They were wrong! Later on The rib was eliminated and the barrel made a bit heavier for the Mohawk series.
Recoil in 308 was noticable as was muzzle blast but the rifles shot very well, as a rule, and worked as intended.
With a little different stock, a metal guard and floorplate, and a good recoil pad, the 600 would be good rifle today. If the 308 was renamed the Mini-Mag, it would be capable of killing today's big game animals and would sell pretty good!
Few people hunt from horseback anymore but a short, handy, accurate rifle fits on a Quad or carries on a backpack pretty well too. The 600 was the fore runner of the "scout" concept.
In later years the 600 went from being a special purpose rifle to being an econo=rifle and suffered a bit in the process. It was still a compact l;ittle rifle but finish was rougher and the birch stock didn't have many fans.
If I were to make a 600 today, I would make it in stainless with a laminated stock (black/green). I would want to try and make the bolt handle a bit more attractive but keep the forward slant and make the rifle even more of a bullpup design if possible. No ribs or plastic but a rugged set of open sights for emergency use. I think it would be a decent seller. I would NOT make it a short Mag! Regards, Bill.