The problem with most(all) verticals is that the mower blade is the
flywheel too. I suppose a "traditional" flywheel could be
created......

I have seen references to kits to turn a vertical horizontal, but seems
like a lot of work for little gain.

JW

BTW - I'll be watching this with interest as I seem to have a similar
compulsion. I have about 5 questionable push mowers for no reason
other than "they must be useful for something".