What engine should I use?

What engine should I use?

After a while trying to find a A-Body with no luck I decided to buy a old car to build. I'm building a street rod and I'm not sure witch way to go with the motor. I want this to be a weekend driver. My options are:

1955 331 HEMI 20,000 miles on it (Needs Rebuilt-It's been sitting for years before I got it)!
1974 318 w/340 J heads with around 4000 miles on it!
1972 340 w/340 J heads (Needs 40 over pistons to finish)
(I have 2x4 and a 3x2 intake for the small block).

I want to run the hemi but I don't know a hole lot about them. The small block motors I have a bunch of parts for them. I'm not worried about gas mileage. I want something a little different under the hood. One thing I do know it will be Mopar powered! I'll be using a 727 trans, a 8 3/4 rear with some 21.5" Mickey's.

What do you think would be the best way to go.

Thanks Brian