If you want to go the LS/Vtec route your still going to have to rebuild the bottom end to allow for the higher consistant revving. People say that the LS/VTEC is not very stable and could cause serious problems but if it's done properly you shouldn't have any problems. As for the price differences you should consider that the bottom end needs to be built no matter what and the top end is going to be replaced either way also. I would check into the prices a little closer if your budget is going to be problem since I don't have any real knowledge of an all motor cost. I think it's really left to your liking.