The sleeper for a 5.0 HO right now is an 87-up Lincoln Mark VII. You get the 5.0 HO and the AOD. They have 8.8's too, but in addition to being a 4 link
suspension, it's also air ride too. 8.8 that's closest to being a bolt in is an Explorer/Mountaineer rear. Close, but still needs mods to work (welding) as a bonus most Explorer rears have traction-loc and 31 spline axles, some have discs brakes. No 8.8 will bolt right in. As for other 5.0's ? Any 88-up 5.0 will be a roller block. The cars got roller cams but the trucks & vans didn't get em till about 92 (they still had roller blocks before, but flat tappet cams). The 94-97 pickup and van 5.0 is a real sleeper. These had the hottest roller cam for 5.0 aside from the GT/HO. This cam is just a step below the GT/HO in specs, and will equal the HO cam's lift with 1.7 rockers. Same heads as the GT/HO too. Watch the 91-up rods in them, they're not what they were before. Seen two that broke rods in stock applications, these both had F1TE rods. Cranks are better castings than the older ones though, they quality is so good, they damn near look like forgings. Bottom line is, any 87-up 5.0 is a good foundation for a build up, aside from the later rods.