you can put a 26 in in a 22 core support. my self and plenty of other members have done so.

a change in the raditor isn't your only issue.

air flow is the main problem.

at around 45 mph no fan will pull as much air as is being pushed through by speed.

if at 50 mph your car maintains cooling, then you do not have a cooling system issue.
you have an airflow issue.

while a shroud might help, on boarder line issues, yours seems to be much worse than that.

additional cooling capacity using a 26 inch rad would bandaid the air flow problem.

just cause you don't want to hear it, doesn't make it untrue.

the wrong answer is always, we have always done it like that, and it worked before.

if you can get a giant shop fan and blow air over the rad at idle, you can prove it is an air flow issue. not an engine or coolant capacity issue.