Its hard to figure a price, well you can look on machinery trader and similar, though those prices seem to run high, with those pads on, I'd guess lower and these run locally from 5k to 10K and maybe a little more, which really does not mean all that much. There is always mention of the 4 in one bucket making them more valuable, or it has to have one to be useful, the latter of which depends on the use its needed for, I have ran plenty of 955's and 977's none had the 4 in one, got by just fine doing full time work 6 days a week.
The pads, they are swamp pads, and I don't ever recall seeing them on a crawler loader, nor have I ever seen a crawler loader working in those conditions, nor a factory LGP crawler loader, again that might not mean squat either LOL ! Interesting you posted a photo though. Unique and maybe there is more to that than I have seen.
I don't believe those would last long on hard ground, or in regular soils, depending on the use, more so if its not used on soft ground and I question how well this would work anyway, having a standard front bucket. Most LGP dozers will have a light blade, same model but not LGP will have standard pads and standard size blade, be it 6 way or whatever else may be available to fit the tractor.
The rule of thumb is to use the most narrow track pad that you can. Preferable width is what matches the work you want to do, hard ground = narrow, soft ground = increased width for wider weight distribution. For this tractor if its to be used in a gravel bank, clearing, miscellaneous use, demolition, etc, should have standard double grouser pads that most of these tractors came with anyway. Amazing they are on this tractor as it may not have been designed to allow for much extra width on the pads. I have seen dozer track pads on these, where slippage was an issue, same with excavators in harsh conditions.
I'd offer less for it, if its in decent shape and you can find a set of pads or a complete track chain and pads that are in decent shape, you could have both options for the tractor, or sell the other set to defray the cost of putting what you want on. I would check the rollers, and sprockets for wear and see whats what before changing anything or considering making an offer. It might be a matter of removing the pads, installing new bolts and good used pads. Be nice to find a set of tracks and just change those out, will save you some work on changing the pads, and that is if the track chain is standard just with swamp pads, likely to be just that or so I would think.