I looked a while back on riser extensions. I *think* need 4" or more. I think it's $1500 to add 6". Assuming all other parts are copacetic. That said, it has 200+ hours on this install. The local mercury place says make sure the anti-reversion flapper in the bullhorn is in good shape. That is the first/best line of defense, according to them- and the cheapest.
Oh yeah, GM performance Products has sodium filled vortec valves. $50 a pop at Summit racing. I think I would go Inconel with aluminum heads first. After I stumble across some unused cash.
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