I don't know if I'd be investing that much money in covers to hack 'em up. Edelbrock makes tall die-cast aluminum covers for a lot less money. They also have to be hacked up for breathers, but the initial investment is palatable, 98 bucks for polished or 74 bucks for black. Get the breathers/tubes you plan to use and cut holes in the covers with the appropriate size holesaw chucked up in your 3/8 drill motor. Here are instructions from Edelbrock of how to install baffles in their covers....
http://static.summitracing.com/globa...lve_covers.pdf
And here are the covers.....
http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku