Find a better machine shop first, if everything was done right the first time you shouldn't be having the problems you have had,On a 230 with hyd. lifters you should have about60-80lbs of spring pressure,I dont think you had too much spring pressure, most likely you didnt have enough,you mushroomed the tip of the valves and thats where that comes from,not enough spring pressure, you also broke a spring,when people do valve jobs they sometimes forget to check spring pressure when putting the head back together,they do a valve job and sink the valves into the head and that loses pressure of the springs,they make a spring shim(VSI) to get back the spring pressure you lose. as far as the "polishing" of the cyl. walls goes, I would think that maybe you have washed the rings out with too much gas,fuel. Yes I would check out your carb. Too much gas will take away the lube that the rings need to live, there is nothing wrong with molley rings if the cyl. finish is done right and you dont wash out the cyls.
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