To answer the OP, 2800 Gohan = 2800 Gohan.
Seriously though, I'd say the Masenko shouldn't really provide a significant amp. Pushing back Piccolo so low that he barely passes the 2k threshold seems to be a major lowball since off guard or not, an attack from him was still enough to faze Nappa slightly. Gohan shouldn't have enough capability in Ki control to amplify his attacks at that point and the Masenko was just a way to channel forth the full power of his rage boost into one attack, especially considering the only times he uses it in canon is as part of his rage boosts, thereby showing no significant difference between his rage boost and the actual attack.