Was a Ron Newburg (Canadian Aero Engines - Orillia) staple for a while, thanks to an abundance of 540 cylinders around. One of my customers airplanes. It seemed to have some "balls". I only flew it back to him after rebuild, 25 miles. Two take offs and landings so no true testing on my part.
Lycoming thought modular when they designed their engines.
A 290 with 2 cylinders added = a 435 (as in the Stinson L5)
320 with 2 more cyl's added = 480. Dunno if they made any direct driven 480's, but there's a lot of GO-480's.
A 360 with 2 cylinders added = 540.
a 540 with 2 cylinders added = a 720 (as in the Commanche 400).