joelh
the cam base radius,s are very uniform, so just swapping cams "usually" gives no problems with valve clearance.
but valve stem hights can be quite random so mixing shims can b###er up the clearances so be carefull.
theres a guide on cisco micra.
you should end up with exh lobe just about to touch the shim at about 20 deg atdc and inl lobe just about to touch the shim at about 20 deg btdc.