That one's priced about $100.00 or more too high unless it's needed for a numbers-correct restoration. Definitely stay far away from the single plane manifold he's offering unless you never intend to run the engine below 3K RPM. The 300 HP engine offered in 64 had the original "camel hump" heads, and the only one that was actually factory rated at 350 HP was a limited-production Corvette option. The 300 HP engines were available in the Impala body styles, beginning in 63, IIRC.
Plan on spending somewhere in the neighborhood of $4-5K, minimum, to build the kind of engine it seems like you want, and that's if you do most of the labor yourself. The round track race-winning 350's I built a few years ago sold for around $15K.
Jerry
