What do you mean by "it didn't fit"? Was the base too big to fit in the bottom of the tank, or was it too small?
If the base of the clearo fits too loosely in the base of the tank, you may be able to do something similar to what I did.
I modified a couple of the original smoktech DC tanks to accept the innards of a clearo by cutting the tube of a stainless steel carto to length. Insert that into the base of the tank, assuming it has the inner o-ring to seal it to the tube, and then insert the ce2 innards into that. You will also need a piece of the tubing for the top of the tank to accept the ce2 seals and a drip tip. I made the tubes length so they protrude out of the end caps about 1/8 inch, YMMV depending on the length of your tanks. This was to make everything line up for the seals at the top. You want to make sure the overall length of the tank with the tubes is the same length as the ce2 plastic tube.
I used those for a while until I discovered the original Arry tank which was made to accept the ce2 innards. He quit making them for a while but now he has a new version which has 2 base caps for slightly different size diameters of clearo bases. They are kinda pricey, but I've had 3 of the originals for almost a year now with no issues.