PKDM 1.6 G16b engine are hardly found in scrap yard...mostly available are G15 with similar head.
Post 2001 G13b are with waste spark technology earlier it was equipped with coils at a side of head, in contract G16b is with distributor, there is no dedicated CAM sensor as ECU gets CAM position data from disti.
to fit it over g13b maybe you need to do some alteration in wiring to feed ECU with required data...
G16b is a screamer but with hell of torque...till 2010 when i had been using it as main car and was in top notch condition, i smoked all sort of cities, xlis glis of that era...loosing only to VTI due to vtec at higher RPMs civic maintained its power band, however suzuki kinda start loosing it....still it packs a little surprise when u floor it..
no idea abt head cost, but my guess is that it will be within 15k limit