I think Eric is probably the one to answer this question definitively but Volvo, like some other Euro manufacturers, may use the cylinder closest to the flywheel to set timing when assembling the motor. My only experience with the B16 was in a 1960 544 I owned briefly long ago - but did not get into any of the mechanicals. The poster should be able to just switch wires around at the distributor cap and shouldn't have to do anything with the drive unless not being original is a big issue. #1 and #4 pistons work simultaneously so it makes no difference to them. - Dave