Vibration and ride quality

[69SCSS]

hey guys, now that I've driven my truck about 500 miles I am slowly working out the kinks and wondering something. While I don't expect my '68 to be as smooth and quiet as my '02 Silverado or my '11 xB, I'm not sure what's "normal" for the truck. I know it's short wheelbase so it's going to be bumpy. What I have are some vibrations that only happen occasionally, and only at highway speeds. Above 55 I get what feels like a front end vibration that goes in waves. Beyond that I get a little bit of lateral shake, but that's a lower magnitude. I am suspecting that my front alignment is not quite right. I had it done when I had the 402 in the truck and never got it above 40mph while it was running, so I don't know if it had the same issue then.

I plan on taking it to the alignment shop again and have them check it, but what is normal? I would think the truck would at least roll smoothly up to 70-80mph?

Helpful specs: All new front and rear bushings, bearings, etc. 3.5 / 4 drop with 2.5" spindles. Manual steering.