There is no doubt in my mind the 2320 would suit your needs. If the 2520 can do it, the 2320 likely can, too. There are some important considerations to keep in mind here. First, the 8n was really a tractor. It is heavy, which is good and bad and has about three more PTO HP. I doubt it makes as much torque, but we do not know this. The 2320 is a lighter machine with four wheel drive. The MFWD will make it behave as a tractor that has 7-10 more BHP, or a 30-35 HP machine with two-wheel drive--except powering implements. The 48" brush cutter is about the biggest this machine can handle and not bog in heavy cutting. It can handle a light LX 60" cutter in very light duties, but I would not recommend. If a company made a 54" cutter, that would be ideal for this type machine. Perhaps there is one out there. I run Rim Guard and two rear wheel weights each side on my 2320 and it weighes around 2200 pounds with this combination and no attachments. In my opinion, one would need to step into the 3000 series machines to achieve much more capability, though the 2720 has 31 HP and could easily power a 5 foot cutter, just not the MX level (too heavy). My personal favorite of the 3000 series is the 3320. It has plenty of attachment power, heavy duty frame and for the features one gets it is not that pricey. The 3520 and 3720 do offer more PTO HP, but not enough in my mind to justify their additional cost. I do take some issue with the poster's opinion that the 2320 is "a lawn tractor." This simply is not the case. The 2320 is a true compact tractor and will work any lawn and garden tractor into the ground three Mondays each week.
John M