[pprince]

Not quite the same block. Boring out the 260 to a 4 inch bore would leave the sleeves perilously thin. You need a 289 block. Their sleeves are thicker

Paul
1965 Mustang 2+2
1989 Mustang GT Convertible
MCA #27261
MCA certified judge for 65's and late models

 

[390fastback]

They are the same in that they are the same style. To over bore it that much might cause you cylinder wall thickness problems. Consult a machine shop or someone here that might know.

68 fastback, 390 4V premium fuel
80 5.0 hatch, just finished
91 5.0 coupe, daily driver
84 RamCharger 4x4 extreme mudsliger and winter junker

 

[VictorII]

Putting in an early 302 is a bolt in. The 269, 289 and early 302 are dimensionally the same. Problem is that you (probably) have a 5 bolt bell housing so you're stuck with hopping up the 260 (Ford got 260HP out of them for ralley racing) or trynig to find a 5 bolt 289 that is rebuildable. If it were me, I'd consider hopping up the 260. You can use most of the tricks that are used on 289s and 302s except bigger valves in the heads. While they can be ported the valves are smaller and closer together if I remember correctly.

...modified '65 convertible...

 

[Mustangerbob1]

You can also use the 289/302, and just change the torque converter cover (bell housing) off the C4.

Bob Hendrick
[email protected] ebay +82
1514 Braeburn
Richardson TX 972 783 4731