Spark Plug Replacement

I also just bought 6 of the NGK 3459'sSaturday to use in my 64 225. (complete rebuild) These are peanut plugs with 5/8" hex instead of 13/16". I know to remove the gasket but comparing them to original style plugs, the seat has a much smaller diameter, eyeballing them side-by-side, about 1/8" smaller diameter.

My question is will the smaller diameter have an adverse effect on the sealing of the spark plug tubes? Will it tend to tear up the mating surface of the tubes? My original tubes are really in nice shape and I'd hate to ruin them.
Thanks.