[Franke]

Wow its been awhile since I played with those engines. The 283 had possibilities in that there were 2 years of them that had a dished bottom and can take a small journal 327 Crank. With a set of 307 flat top pistons you end up with a hipo 307. All of that is stock stuff. That 283 block was a heavy weight casting and could be bored to.120 with out losing strength.
The 350 has loads of potential for a build without breaking the bank. Just look at Summit, Jegs etc. You can find almost any combo you want.
The 400 I believe might have siamesed bores so you need to be careful on which heads you use as you can blow up the radiator as my friend found out in his 57 Chevy. Seems the 400 has steam ports in the block which need to match up with the same in the heads. The 400 has some potential but I don't know if it is as much as the good ole 350. I think the stock 400 cranks were nodular iron too but not 100% sure. Maybe some others here can chime in.