Well if the full shaft is inside the coupling then the shaft 3-4 inches long that is inline with the 3” shaft that appears to be on most of the replacement engines. Specs on the BS 675e say true shaft is just under 2”. I may be good if I go with longer shaft. Just don’t really want to build engine up any higher with washers, spacers, grommets or anything else if I can help it. If engine is any higher it would be in the way I think and I like to do things ‘aesthetically’ you might say. Would grind down the shaft before building up engine mount to take up shaft length I think. When I get my next burst of energy will most likely take engine apart and replace valve as you guys mention parts are inexpensive.