The 5.2 has been running awesome- and completely problem-free since I've dropped it in. Doesn't consume oil or coolant, has smooth, reliable power, and overall has been just fantastic for a junkyard engine (remember i dropped it under the hood with 177K miles already on it, and it's acted anything but old and tired). That said... if it ain't broke, fix it 'til it is!
Just picked up a 5.9 Magnum engine for $250, out of a '96 Ram 1500- I'm going to have it built by a local shop, putting a stroker crank in to make it a 408, which is a popular rebuild option for the 360 (5.9) motors. I'll have it built to be internally balanced so that I can re-use my current flywheel. I'm guessing the AX-15 will likely not last forever behind it, so I better start saving up for one of those built NV3550 Terminator transmissions.... but we'll cross that bridge when we get there.
In the meantime, I'll send it off to the machine shop over the winter, so stay tuned, in a couple of months I should have a small block turned big block under this hood. The best part is that it will be a direct swap in place, I won't have to alter a single thing under the hood, just pull the 5.2, replace with the stroked 5.9
The 5.2 motor is and has been awesome, I just find the allure of a 408 cubic inch motor too much to resist... stay tuned