I am wanting to install 3" blocks in my 54 Ford. If i do this, someone said I should install a panhard bar to prevent side to side flex. Thoughts?
No I didn't have to, I don't think you'd need to raise the floor in a shoebox either for only 3". I know a few guys with 4" blocks in shoeboxes and they bottom out a bit with people in the back but have no issues when driving solo. With 3" you won't have any issues, I used the stock shocks also and haven't had any problems. In the front I used Aerostar springs and cut a half coil, it dropped the front about 3" maybe a hair more. Drives great.
"Someone" is wrong. A block simply raises the axle, lowers the roll center, and does not create any movement that would require a panhard for location. It's a block, not a pivot.
At stock height the rears were a bit finicky to get out, 3" is abit of pain but is doable with little effort. That's the main reason I didn't go 4" on my daily.