A leak down test of the cylinders will be way easier than pulling the heads of for starters . You might be lucky and just need new chains and guides .

And the 4.4 engine might work out as the capacity is only 25 cc - ish per cylinder less , use all the 4.6 manifolds etc . On the other hand you might blow the 4.4 quickly due to overfuelling but a remap of the ecu might work if you find someone who knows the figures to detune your ecu .

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