Originally Posted by big_wasa

Spacer, what ever is to hand. It needs to be some kind of metal as the starter is earthed through it. So alloy or steel.

You realy will need to add a good litre to the capacity.
More important will be adding baffles for track work.

If your making spacers for starters then have a look at the zetec starter mod. It will make the sump much easier.
Old sierra starters can struggle starting hot zetec's not helped with sitting near a pan of boiling hot oil and the exhaust.

for every thing you want to do there are a dozen different options depending on using your hands or your wallet or something in between.