Any small block Ford will fit in you 67 Mustang. If you end up with a late model 5.0 engine then you will eather have to change your radiator to a late model style (you can find these at AAPD.net) or you will have to replace the timing cover and water pump on the 5.0 engine to the earlier style to make it work with your existing colling system.
Source: AAPD.net and AverageJoeResto.com
Will a 1998 3.8 mustang engine fit in a 2000 Mustang 3.8 engine?
Not directly, it will take a lot of modification, time and effort to achieve that swap.
the 427 was the largest engine the mustang was made to fit
No, the Boos 429 will need mods for the engine to fit in the 1998 Mustang.
yes, the 5.0 (302) will fit in a 73' for sure.
yes, it will fit in
NO
no cause a 1994 may have a bigger engine
Yes a 429 would fit into a 1969-1970 ford mustang without no engine compartment mods
yes, a hatch from a 1979-1993 mustang will bolt directly to any of these model years
Not directly, no.
A 460 big block.