The 7500 is, if I recall correctly, a 21hp tractor, that would be very marginal for a 60" finish mower. Under ideal conditions it would run the mower, but if the grass gets tall, has a high moisture content, etc, then you will be pushing your luck on that size deck.
I own a TC24D and use a 60" Befco finish mower with that tractor, it handles the mower well and RARELY bogs down, but it can bog down. Also, I had to install an extra 100# of weight onto the front of the TC24D to hold the front end of the tractor down when using the mower deck because the deck easily lifts the front of the tractor off the ground. I don't know the weight of a 7500 versus a TC24D but I suspect the 7500 would be even lighter. There is a rule of thumb that I've heard several times, it says you need 3hp to 5hp per 12" of mower deck. If the 7500 has a 16 available PTO hp, that would mean that a 48" deck would probably be a better fit than a 60" deck if you use an average; that also matches up with my experience running a 60" deck on my TC24D which has about 19 PTO hp.
I also have a B2910 which is the full featured version of the 7800, I think the 7800 would be a nice choice for your situation. If you want a more manuverable tractor, I would opt for a TC24D, it is less power than the 7800, but it offers plenty of power on a smaller frame that is tighter turning so mowing is easier. I like my TC24D better than I like the B2910, especially for FEL work because the curved hood of the TC give a better view forward. The B2910 has a big flat hood and big square loader arms that limit forward visibility.
Bear in mind that you are comparing a fully featured or deluxe version of the New Holland to a bare bones Kubota. The bare bones New Holland would be the TC30, it would be a direct comparison to the Kubota B7800. I'm not really sure if the B7500 is a bare bones unit, but I think it is, I THINK BUT I'M NOT SURE that a more reasonable comparison would be the B2410? or B2610? to a TC24D in terms of both power and features.