Just buy the LS/Vtec conversion kit, It comes with an oil filter adaptor plate so you don't have to tap the head. You will also need to upgrade your rod bolts to ARP. Best to install a fresh set of Rod and Main bearings while your in there. Checking clearances with plasti-gauge is harder with the engine in the car. And don't forget to buy an ECU or something to tune with. You can buy just about any Vtec head here: http://www.jdmshit.com/parts/components/index.html

ITR and B16 heads are the same casting, but different components. If you plan on modifying in the future, I recomend getting whichever has the best price. If your plan is to leave it alone, the ITR head is a great option. Don't forget about your intake manifold, the GSR head must have a GSR IM.