'59 camaro clipped, ride improvement

[LSXapache]

So I've had my truck on the road for a little while now and I'm finding myself wanting to fix a couple ride issues I'm having. First is noticed on the interstate and bridges that dip at the start or end. When travelling at highway speed the truck will bottom out on the dips a lot of the time, on the interstate it will often get into a rhythm of floating up/down with the concrete sections. Since those issues seem like shock issues to me I'll state that I put cheapo oreilly's shocks on when I installed the clip. The next issue happens at any speed and from what I can tell only changes with road conditions. I get a side to side shimmy that shakes the entire truck but it is not felt through the steering wheel at all and steering isn't affected. It get annoying because it rattles the side windows(haven't gotten around to installing felts/seals yet) and doors(needs hinges and latches). The shimmy happens on roads that are relatively smooth(riding in different vehicles on same road I don't feel a thing) but I have noticed on very smooth well maintained roads it hardly ever does it. Also it seems to not handle potholes/bumps well I'd equate the harshness to the old CJs I've owned. Look forward to hearing yalls ideas and advice.