Is it absolutely necessary to drill the extra holes on the deck face so they intersect and match the holes in the head gasket and head face, on a "Mopar 340 Resto Siamese block". I have read the cooling section of 'How to build big inch Mopar small blocks' and Jim suggests you should drill 2 holes between the cylinders front and rear (yielding 6 holes each side total) at 55 degrees so that they intersect to allow water flow. And then restrict the big holes front and rear at the deck face by screwing a plug in with a 0.125 hole drilled in the plug. Just wondering for a street / strip engine with 600ish HP, if this is worth it or necessary. 400 Chevs are Siamese and don't seem to have over heating issues.

Thanks
Macka