Re: 4.2 liter engine, swap for 4.6?
I'd see if you could plunk in a newer 4.2L. That way you should be able to retain all the factory mounting points. I'm certain a 4.2 from an F150 would work just fine. Some things you may need to keep from the current 4.2, like oil filler tube etc. Moving up to a 4.6 may require a number of changes, including possible suspension tweaks. Make sure whatever engine you get that you get the computer and wiring harness, or you'll more than likely have problems running the thing! If you are really wanting a V8, I'd go all out and get a 5.4L with some performance goodies. I can't see justifying going from a 4.2 to a 4.6 for only 400cc more volume.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!