I got the trailer stub axles I've been waiting for this morning. So this afternoon I was able to start the front wheel conversion.
First thing was to modify the stub axles. The spigot on the end was cut down to 1/2" long then bored out 3/4" by 1" deep.
Next remove the existing front wheels and modify the axles. These were shortened to 3/4".
The modified stubs were located on the cut down axle and wheels put on to see how things looked. Things looked ok so axles removed and stubs welded to them. Then everything put back together.
Still to paint, grease and adjust, but I think it doesn't look bad. Though I did find the left hand wheel has a slight run out.