Sounds good. I assume you’re playing SF2: Turbo on the SNES. Aka the HF port? That’s a great version of the game. Nobody’s really over-powered in that game, so you’re good to go as far as balance goes.
4/7 is a pretty long set. Depending on how many players you have, this could end up taking several hours or more of your time. If you want to do some rough match, calculate how long it’ll take for the average Ryu v. Ryu mirror to finish in a 4/7 set multiplied by how many matches you’re going to play. Assume two scenarios: That one player will win 4-0, or that it’ll be 4-3. From there, you’ll get a min/max of how long it’ll take to finish your tournament. If the average between those two is WAY too long, consider using 2/3 or 3/5 instead.
Round robins never end in a tie for 1st/2nd. A way to avoid ties for 3rd and below is to count the number of GAMES that each player has won in a given set. Whoever wins the most games will take the higher spot. If for some reason why win the exact number of games (which is unlikely) then you count the rounds. This is almost never necessary.