I have one for my T140, and ist really well made. no sprag clutch but Bendix Ernst H (germany) makes a similar set up. to go on the generator platform, but has changed the castings heavy. not fitted yet, to bussy....
To my modest opinion the originally made by Sam Manganaro (i thought so) with the HD Sportster unit is the best one, although it needs to change the underside of primary cases, and a shorter gearbox layshaft. and lower G2 plate, all good fun. oh and dont forget the decompressor, either HD solenoid with delay on ignition, or as per original. and sprocket M=2,5 with 74 fits (bit bigger as 72)