Any issue for putting in a larger Radiator ?

Sorry for creating a new thread about my radiator. Made a bunch of calls, some trying to say "too old nothing will work", to others saying you can use a similar radiator and giving me options. One guy said bring it in, he will send it to be tested and then they will offer to repair (if possible) or recore (which is insanely expensive).
I have been able to find suitable replacements in copper/brass (new) for under $200, main ones I am looking are by Spectra Premium. But this is issue: my 66 dart L6 3.7, no A/c, has the smaller 19in radiator, which then has mounting bracket that extends it to cover the opening which is actually almost 23in wide. I see that there seems to be 2 sizes available, one is 18 7/8, the other is 22 3/4.
So question is, if I put the 22 core in, will I have any cooling issues? will the fan still do the job? or do I then need a bigger fan??