Spot wobble was used in a few UK sets. With larger screens the 405 line structure was very visible. Still not common.
The Aurora WC-01, of which only a few were made, will convert NTSC to 405/50. The modulator output is correct too. You would be very lucky to find one.
The field timebase will lock to 60Hz if necessary.
There are various published designs of System A modulators. From simple designs using crystals and 1496 balanced modulator chips to the universal modulator chips used in the Auroras. It's more or less essential to use a separate sound modulator, whichever approach you use. I wrote this article in 1989:
https://www.borinsky.co.uk/simple_channel.html David Looser's design is similar but earlier:
https://www.thevalvepage.com/project...at/modulat.htm
Several people in the UK and Europe have generated 405 (and other standards) by using a VGA output from a graphics card and setting the modeline. I have never tried this. I think there is some writing about this on my friend Peter Scott's site:
http://www.nostalgiatech.co.uk/