need help Bad-excuse me for being stupid

A "V" series plug is a TAPERED SEAT plug

A "J" series plug is a GASKETED, FLAT SEAT plug

They are NOT NOT NOT interchangeable.

What do you have for heads? I'm not familiar with some of the late model, IE, Edelbrock, etc, heads. Maybe some of them use tapered seat plugs. All the older B/ RBs used J plugs

Some of the later model motorhome, etc heads used peanut plugs