I have an old book for the 258 and it does have some 304 specs.
Book reads N-12Y as a plug type.
Question, what plugs are you running on a stock application (if that means anything anymore :) .
All I have is a Accell coil and the standard cap/rotor and 7mm wires.
The cap/coil are new, w/the accell coil, should I open the gap more or keep it @ 0.035 as it reads for the 304cid.
Thanks again,
Jim