I think all the 235's had hydraulic lifters by 59, if it's got the original engine. Does it rattle all the time, or change note warm or cold? Don't try to adjust the lifters while the engine's running. It just makes a big mess, and frustrates the mchanic! There's a good procedure to do an adjustment on a warm, stopped engine that works just about every time.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!