Hey guys,I have a 65 383 Polara convert, all original including top. I have owned it for 20yrs. The motor hasnt been touched until I owned it. Only mods are a electronic dizy, and a roadrunner cam and a set of 915 heads that I paid to have them redone before I installed (cost me a [censored] load at the time). I had a custom dual exhuast that soon rusted and just recently installed a factory OEM system from Waldon. Now thats its quite. I hear a putt, putt putt from the exhaust and know immediately that its a burnt valve. I only had 10k on the new 915 heads. Getting screwed once I now want to be sure I do It right this time.I want to rebuild the 516's CC and sell the 915's. What should I have done to the 516"s besides the valve job, seats and brazz seats? What springs should I order and should I just shelve everything and buy aluminum heads?