Seems to me the 2.5 four cylinder and the 2.8 V-6 have the same bellhousing pattern,but it won't fit a straight six or V-8. The newer Straight sixes (after the 235) and V-8's have the same bellhousing pattern and can use the same flywheels and clutches.
This'll be an interesting swap. Keep us posted on your progress,and don't forget PICTURES-lotsa pictures.
Speed

1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck