4321zip,
SOU is licenced up to 757 size, and in the Summer (well, last Summer anyway) saw Britannia 75's, Air Europa and Air Malta 73,s (all the way up to -800) and Iberworld 320's. Spanair 320's are operating to TFS (albeit via outbound techstop in Nantes) during the Winter.
With regard to 146 performance (payload/range) off the SOU runway, I guess Rawdata is best qualified to comment.