Note that the SL-B303 usses the FG Servo so you may want to check for speed issues BEFORE you buy it. These FG Servo BD decks are prone to speed issues as the speed pots get dirty. Also the IC chips tend to fail on these... I would say avoid it. The B303 was the last BD deck from Technics with the S arm. The SL-330 was the better version of the B303 in terms of BD geneology (SL-330, SL-B3, SL-B303).
The speed issue can be cured by cleaning the speed pot, but for the effort, you should just look for one of the DD versions of the B3 series decks which are the D3, D303, Q3, and Q303. These are decent enough and will not have the speed issues as the BD ones tend to. Remember, Technics sunk all their money into DD first. BD was an after thought if you will that did not come out from Technics till 1976.
Enjoy