79 Bob Glidden Small Block Pro Stock

NHRA went to 500 in. engines in 1982. Destroked 396 Hemis were popular, but John Hagen was making news by setting the MPH record with a low deck big block modified to accept Hemi heads before that. Charlie Malyuke was behind the mod. Don't know off hand how small they went with that.

I believe Paul Gentilozzi got Gliddens Arrow and parts after he went back to Ford.

With a pound-per-cubic inch format, a smaller engine is more efficient. In other words, it's usually easier to make more HP per cubic inch.