1970 Dart Dash

Hey all! I have a 1970 Dart Swinger. I want to swap out the old banged up gauges/speedometer with a new custom one. I found the new one I want on Classic Industries but noticed it says it will only fit on A-body’s with original square speedometer. I have a rectangle style and it says the new one will be too narrow. Has anyone ran into this issue or had any luck? How hard would it be to find a dash with the square speedometer? I’ve attached my dash current and the panel I want to purchase.