engine swap?

I have a 1968 Ford with a 390 mildly built and I have a chance to get a 1968 429for it. Is the 429 a better motor than the 390? Is it worth it?

Yes, and yes. The 429/460 is a big improvement over the older designs. They are torque monsters.

Don

Depends on the 429. (And the 390!) Is your 390 in good condition? If it is, you will go to a lot of effort for little gain. A well-built 460, now, that'd be a whole 'nother story. Of course, so would a 428, which is a bolt-in swap, unlike a 429.

Put any kind of Lima motor 429/460 in place and you'll throw rocks at that 390.