Can anyone recommend a peep, aperture or ghost ring sight for permanent installation on a CZ550 receiver? I'm building a 404 and may not use a scope at all. I appreciate your input.

Ashley makes a simple, sturdy peep sight. The model for flat top receivers should work fine on the CZ, but any good smith should be able to take the guts out of the sight and mill them right into the square bridge.

Sometime ago, I finally got a Merkel drilling in 12x12x9.3-74R, something I have wanted for years. A machinist built a custom rib which slipped onto the modified rear section of the elevated rib between the barrels, this was also bonded with some sort of super-epoxy and screwed on with custom, fitted 8-40 screws. He dovetailed it for both Ruger factory rings and the "guts" from an Ashley ghostring sight, then built a custom ramp to hold a European style blade front sight. This is similiar to KurtC's suggestion and I describe this to advise you that this can be done and works extremely well. I have both irons and a scope ready to go, which in B.C. hunting conditions is a very good idea.

I have other Ashley ghostrings on special-purpose rifles and highly recommend them, they adjust easily, are quite rugged and really do work.