Why would new shocks make the ride WORSE?

['68OrangeSunshine]

Hey Kurt, I just put new KYB 344068 shocks on my '68 C/10 Stepside. They work great. Lost a lot of shimmy on the front end at freeway speeds 65-80 MPH. My KYBs are black.
My mechanic also helped me install new hood hinges and springs [ GM, but made for our vintage in the Early 2000s -- I have P/Ns]. Before the hood wobbled at speed. It was hard to close -- had to be slammed. And the rear stood up 3 to 4 inches. Now, I can close it with 2 fingers, there's no wobble and no rise at the rear.
Rear shocks were ordered from a different vendor [RockAuto] and got in yesterday.
P/N: KYB KG5416. They are a 3-level adjustable shock for Rear, Coil, springs. I will probably set them for Medium. Can't get my guy to come back til Monday.
Stepside is about to roll thru 400,000 and needs to pass Pima County emissions before re-registration, Due 31 OCT.