I don't think I have ever seen a 40-pin DIL package that wasn't 0.6" wide. That's a constraint imposed by the lead frame, and while I've seen spec's for some high-pin-count parts in 0.3"-wide parts, mainly buffers or level shifters, I've actually never seen 'em "in the flesh." I have, of course, seen the 0.050"-pitch SMT J-lead parts that were common a couple of decades ago, but not the standard 0.100" (2.54 mm) pitch parts in greater than 32-pin DIP's.

I recently had to use commercially produced adapters for a 44-pin FRAM with a 16-bit datapath. That replaces two 32-pin 8-bit-wide parts, but the reason I used it was because I wire-wrapped the board in question. The production version would certainly be with SMT's.

RE