I’d say the luggage issue (checked-in vs carry-on) is critical in such a short connection on two different tickets.

Provided your incoming flight lands on time:

1) With carry-on, and online check-in already done, you will be ok. You’ll have to clear immigration and customs at EZE (think 40 minutes approx at most.) and then go through security, which on domestic flights is quite relaxed.

2) With checked-in luggage on 2 PNRs, you’ll have to wait for your bag –delivery at EZE is unpredictable, it can take anything between 5 and 45 minutes–, and then rush through to Terminal C for check-in, which is some 500 meters away from the main arrivals area. In that case I’d say 2.5 is very tight.