hole in my head

Clean it, enlarge it, weld it, pressure check it.

The Edelbrock open vs closed chambered heads issue is one of the open chamber for the early 340 pistons that come up above the blocks deck height. The chambers are machined bigger for there clearance. Theres a few more cc's in the chamber for clearance. If you run this head on a flat top (And a max height of zero deck) the comprsion calc's out slightly lower.