I did a Homelite conversion (46 I think) -balanced the flywheel and prop and still have
what I think is excessive vibration. Does the position of the prop in relation to the crank
have any significant affect on vibration ??? ej

As long as the prop is balanced it should not impart any additional vibration to the engine. If you are still getting significant vibration it has to be due to the engine crank and flywheel being OOB. Usually the flywheel is counterbalanced to offset the piston jumping up and down and the crankshaft rotating.