Glenn, if you have access to a large lathe and are a reasonably handy fabricator it`s not too difficult to modify and fit an automotive flywheel and starter, I have done several, firstly you need to determine which side of the engine to fit it then you need to find a starter (min 2.0 litre diesel vehicle) which will crank your engine in the correct direction given that the starter and flywheel is fitted outboard of the Lister flywheel, some vehicles have the starter mounted next to the engine some next to the gearbox, out of the two one will be the correct rotation for your setup.
You will need to obtain a taperlock flange and bush to suit your crankshaft, the flywheel is bored out to accept the flange which should be a press fit up to the flange shoulder, it can then be bolted or if not enough metal for bolts, welded. Never done it myself but a register turned into the flywheel and the flange bolted into this would probably be as good a job.
The tricky bit is making and positioning a starter motor mounting bracket, this has to be substantial and very rigidly fixed, if not it will flex and the starter motor will jump out of mesh on compression, probably best to allow a bit of adjustment on this to allow for the correct meshing to be set although this is not crucial it just makes an awful noise if not.
Mark.