As long as the new plugs have the same threads and the reach is correct, don't worry about it. Compare the new plugs side by side with the ones you have in there now.

As long as your 3/4" reach plugs aren't hitting the top of the piston, don't worry. The longer reach plugs improve combustion efficiency.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)