A swing from cold to hot with a increase of a half inch would be normal.
Once the car is hot does it remain at the correct hot level?

yup its stays when hot...but before I did the work it would go up and down an inch or maybe more.....everything else seems normal

I would be watching for proper operating temperature when hot and maintaining that temperature; not so much of how much the overflow tank rises when hot or drops when cool. Most 3800s run around 200 degree on the gauge, I will be looking to see the needle hang at that number after warm up and staying at that number. If you are running under 180 after warm up I would be looking into that. Maintaining 195+ operating temperature would give me confidence the cooling system is sealed and running properly.

I would be watching that you are not losing coolant, more than anything else.....always check cold......radiator should be full, and the reservoir at the cold mark.....

Did you replace the radiator cap when you did all of this work by chance?

nope same cap and it IS working properly...it holds temp when running down the highway..was running 197-198 the other day but today it was only 2 degs so it was like 188...it is a brand new stat 195 deg

As long as the engine is staying at its normal operating temp, and you are NOT losing coolant, you are fine.