If funds avalible, then get aftermarket heads, good time to upgrade..
AFR (my 1st choice), Edelbrock or possible TW.
Was a leak down test done? How does he know it is the valves?
Good luck.
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1994 Cobra Indy Pace Car Convertible # 591 of 1000
2001 Cobra, #2001 of 3384 verts, Black on White, Born on 6/01/01