closed chamber vs open chamber edelbrock heads
Ok, so I'm straight on this.
You want to modify your stock 340 pop-up pistons to fit the small chambered Edelbrock heads?
While there would be a slight performance gain due to a lighter rotating assembly, as in spin up the RPM quicker, the cost dosen't really justify the end. It would be better to re-do the bottom end with bigger weight savings in mind not to mention a stronger piston.
Some people talk about piston to head clearance and quench as the same thing.
This is true to a point. The quenched area is of the piston closest to the head and is only a small portion of the piston. (on a flat top piston that is.) The rest of the area is more open.
On a domed piston, the manufacture makes the dome to (Semi) fit the stock head. Work is still needed due to things like milled deck/ heads/ polishing the chambers , re-worked rods, etc..
If I was in your socks, I'd go with the correct head (Open chambered) on your pop up pistoned engine. If you change pistons in the future, you can allways mill the heads.