Whats the best? I’ve tried some from Google search but they weren’t great and seemed more focused in fit. I’m trying to see what a slacker headset will do in combination with messing with frame chips.

Make your reach and ett shorter but not by much, will also lower bar height and extend wheel base

Is ‘Bike CAD’ still available?

Could use that maybe do what you need?

Failing that draw the frame up properly using one of the various free ACAD style packages available perhaps Then overlay the different configurations to compare…

bikecad…

Cheers, will take a look.