you need to check the timing stretch to know how much you need, but if you are the original owner of the car and it's at 315K odds are good, you need new chain, new gears, and a retime of the IP.
there are pics online but you can get a close estimate of stretch by pulling the valve cover, and PERFECTLY lining up the timing marks on the cam gear to the cam tower. it will look similar to this -= if aligned the arrow has to EXACTLY center in between the hash marks.
note this is NOT an approved method of checking the chain stretch, it's just going to give you an estimate of stretch. the approved method is to use a dial indicator and remove lash in the valve... then lift 2mm, and note the timing mark, then use a chart to show what your stretch is...
anyway, 315K is likely too much...

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