You're missing the steering column.

Drill a hole though the nearest (solid frame) object, tap it (if you have taps), then install a stop (I would use a bolt, were I in your position).

You have to limit the upward travel, or you'll zoop air into your brakes through a (potentially) bad master cylinder gasket. It happens. <It DOES happen... (Ever see a bad 'brake booster'? With a bad MC? Same thing happens with manual brakes and a low pressure weather front...but... I assume everybody else knew that's why you should flush your brake fluid every 24,000 miles, per my 72's owner manual, as well. )) |=}

I think those may have been racing parts that you ref'd. That happens as well. ;

Upon further review...
I took a good long look at the situation configuration.  Instead of tapping for a bolt, an easier solution would be to tuck a u-bolt over my steering column (which is not stock).  The strap, or if necessary, a made-to-fit piece of stock at the bottom of the u-bolt will be my stop.

Although I didn't used your idea of a bolt, you did provide the inspiration for a solution along that track.

thanks!