If you were running 27" tires, the 3.73 gear would make sense. You are, however, running 33" tires and that will call for a gear around 4.56/4.88 or even shorter if you expect any acceleration at all.

I'd put hard exhaust seats in the heads an bolt 'em on. Larger valves will require opening up the ports and pretty soon, you'll have more money in them than you wanted to. If you want max flow, buy a set of aftermarket aluminum heads that are ready to go out of the box.

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