d7 pins & bushings change

First thing is, how much wear is on the rails and what makes you think the pins and bushes are due for changing? The standard 'sealed' track bushes are longer because they extend into the outer end of the links and are 'sealed' with a pair of Belleville washers, 'SALT' carries a spacer with a rubber/plastic seal around it in the same space in the outer link. I don't reckon I would try machining the end of those bushes off, they are very hard on the outside surface but the sealing surface you finish up with for the seal to run on would not be very wear resistant and quite rough, damaging the seals.
See what wear is left on the rails before making any decision, give us the height of the rails over the pins and the part number on them and we can tell how much wear is left in them.

Well the machine is out in the middle of the mud as it has been raining for hours here so I'm not going out to measure today. I noticed last time I looked there were CAT numbers on the rails at the splice link, not sure if that's rail numbers or just the splice pieces. Right next to the numbers was the word "SEALED" and there's a depressed center washer fastened to the end of each pin with a small slotted screw. I assumed that was a SALT track but maybe the two aren't necessarily the same thing. Are you saying that belleville washers and actual seals represent two different types? And I know my rails have life left but I can't recite the measurement for sure. There's a lot of room between the pin bosses on the rails and roller flanges, maybe close to an inch, but I can't say for sure exactly what the rail height is.

As far as the bushing length goes, I wasn't very clear. I was contemplating converting to non-sealed pins and just wondered if that works on sealed rails or if it's even advisable. I assumed in that scenario you wouldn't have to worry about providing a good smooth seal surface on the "new" end of the bushing after turning as now the bushing would not extend into the outer link and would only go through the inner link. I work in a machine shop so turning them wouldn't be a big deal to me if they aren't too hard to cut, which I doubt. My machine is only a farm dozer, no commercial work, so an unsealed setup would likely last me as long as I would need it.

Please bear with me, I've been around machinery all my life and worked in a shop most of my life, but this is my first dozer. I can probably get more information in the next day or two if it quits raining.
Thanks,