If you know the dimensions of the bearing try Simply Bearings, I have had good service from them and you can find bearings by entering the dimensions, same for oil seals.
I use either Castrol XL or Morris oils SAE30 in my 2 stroke machines. There is an old film on the British Pathe archive which shows an old SIMAR 10 working and that is smoking. The Rototiller is towards the end of the film at 4:10 onwards, I think it may have been filmed at Wembley Stadium.
Not a pretty sight. I assume the big end bearing is a roller bearing. When I had the engine on my SIMAR Rototiller 10 rebuilt I had to have anew big end bearing made. The biggest problem the company doing the work had was splitting the crank at the big end.
Looking good. I guess making the J bolts will require the correct size round bar, a suitable jig for bending the bar and the application of heat to ease the bending process.
Whilst getting an engineering company to make one will be expensive an alternative may be to find a local model engineer willing to make one, worth trying.
The serial number should be stamped into the top of the tube that runs back from the fuel tank to where the gear selector is, it may need rubbing down with emery paper to reveal it. Meetens may have a cylinder head gasket.
