Cutless 86, you may be an experienced engine builder, that I do not know. I
do know that in my days I have built many small block chev motors, but nothing bigger than the 383 with two four barrel carbs..............

If you are not an experienced builder, and you are talking 496 cu inch BB
with lots of HP, you should spend the little extra and have a Pro do it for
you, especially if you are going to put a blower on it.....Either way, you are
going to spend some $$, and the extra money spent knowing it is done to
exact specs will save you money in the long run....

I would take Pat's advice on anything he tells you about the engine you have.