I used the Intersil ICL8038 about 37 years ago. It is obsolete now and has not been made for many years.Why don't you ues an ICL8038 or an XR2206?
I have never seen a similar Exar XR2206 that was available up to about 10 years ago.
Of course some people hoard these parts and sell them later on e-bay and get rich. I should have done DAT.