I think Ken is right on the money with the 351w, I used the c90e-b on my sons 302 with great results(did gasket match the Ports). As far as I know on the 289,s you are correct, of course there are some diff's in push rod holes, rail rockers, and thermacters, also I did read once that the 68 models-C80e-D and-L and -M's had 63cc chambers for lower compression on th 2V engines. Most Ford people will tell you that the only real draw back to production engines are the flow of the heads(mainly the exhaust side), for everyday driveability though, they perform well. Just us fellows that have this high octane blood in our veins, that craves "More Power", are going to change "Henry's" basic design. I think I have rambled on long enough. Got to get ready to go "Racin" this weekend. You know it's sure gettin harder to climb into and out of that car, but I'll keep doing it till the end(The good Lord willing).