Welcome to the club! If your looking for a 2v, keep in mind the years range from 96-04. 96-97 were rated at 215 horespower and the 98's were 225 hp. 99-04 got the PI heads, cams, and lower intake which yielded 260 hp. I would stick to the later years, 02-04. Reason being is that there were slight changes to the water pump pulley and the early engines were made in the windsor plant so it makes modifying and getting the right parts a little tricky if you don't know whats what. Also, most aftermarket parts for the 2v revolve around the pi engines anyway. As far as reliablility goes, like stang bang said, the engine should last for a while. I have a 98 GT with 250,000 original miles with the original engine and transmission; I don't baby it either, but I do maintain it. If you get a 99-04, chances are it will have 3.27 gears which is pretty good on gas. My 98 had 2.73 gears when I first got it, needless to say, it was a pig. But I did get awesome freeway gas mileage.
1998 GT- 5 speed. Crystal White. C&L CAI, 80mm MAF, TrickFlow 75mm throttle body, TrickFlow Upper intake plenum, Underdrive pullies, BBK catted X-pipe, 4.10 gears, limited slip diff with carbon fiber discs, moser 31 spline axles. MM FLSFCs, Screaming demon coil packs, Ford Racing 9mm wires, SR lowering springs, 95 cobra R rims, black, machined lip 18X9's in front, 18X10's in rear, Bullitt style pedals, SVE race seats.