Say 52,221 to 52,241 should suffice even for heavy traffic, although myself am using Azureus (or XBT on old, slow machines) as clients, which both require just ONE port (TCP and UDP) being open.
It does not matter at all which port the other clients are set at... once you aren't bottnecked by either your firewall or your ISP, you should be able to connect full speed to other peers, regardless of the port(s) they use.
Just avoid leechers clients (G3 etc...) or clients with bad bittorrent protocol implementation (Shareaza, MLDonkey etc...) as many trackers have banned them.