the 5 bolt flange is an earlier design and would be generally used with 3/4 inch rollers, the grousers for a 3/4 inch is also narrower, ( now it being tucker sno-cat, there are exceptions) and the 6 bolt flange is the later design and the pontoon they came off of would also take the larger spool, they used the 1 inch roller and a grouser that was a 1/2 inch wider that a 3/4 inch grouser,
there is a difference between the 5 bolt and 6 bolt flange spools, the 5 bolt is smaller in diameter and will fit in the well of a later ( 6 bolt flange ) pontoon but a 6 bolt flange pontoon spool will not fit into 5 bolt flange pontoon.
back to you spools, they look to be as the factory built them, and were not set up for half links, if you were to put half links in, you would need to add the cups and also remove/cut out the metal on the spool so the cup would sit down correctly, so they matched up with the existing cups in depth, yes turning them around in a good idea
as for a better design, what you have is the only style that was made for that set up, and or years that design was used, now the 500 pontoon spool did have a wider and heavier gear drive on the spool, also, on the very early tucker sno-cats, the gear drive was cast steel and set up to take half links, i have seen, what i believe to be replacement gear drives that were plate steel that is wider and much heavier with half link set up.
nice to meet you and your wife at Mccallin'...glad you folks came, fun to put a face and sno-cat together...