On a side note, the actual assembly of a motor is cake. anyone could do it, especially with a seasoned pro saying 'torque this, put this here, slide this over this etc etc'. The complicated part is making everything work together in unison. selecting a camshaft that works good with the head flow and compression ratio, pistons that have crowns that exploit the burn of the combustion chambers and so on and so forth. That part is all taken care of. All the customer will be doing is basic assembly, of probably pre-assembled parts.