drive it till it blows up, if you have never done a swap before (considering you are making a thread to ask which to swap too, not a bad assumption to make) , pick you up a obd2 d16zc , which are direct drop in swaps for d-series chassis , you will have a significant power gain just going to that healthy low miles swap, get yourself a good CAI and full exhaust, pick up any sort of street-able aftermarket cam, good tune, and you will have a perfectly reliable dd'able swap making good power and still economical, when you have the desire for more power from there, slap a turbo on it, call it a day , have under 2k in everything and have nice name brand parts