Picked up a 239 in.40 with dot sights.
Also have a 220 carry SAS with siglite sights.
Both look like 6 front/8 rear.

Will I have any issues with putting 6/8 xray sights on the 220 and using the take offs on the 239, point of impact wise??

The sights will exchange if you are happy with the point of impact.

That's the question. Both 6/8's.
Will the poi change?

No. The POI is the same if that's what you want.