Make sure you get push rods to match the year of your 235. Measure the length of yours and call to be sure the replacement push rods match that length.

http://www.kanter.com/p18-chn.html

http://www.egge.com/site/?d=48&dt=1&SubCategoryId=21

http://www.vapinc.com/chevy/Valves%20and%20Parts/main.html

Rockauto.com has them at good prices for some years.