Current 'best' aftermarket non ac heater core?
Just pick one and go with it. Like RRR asked- make sure it is in stock.
I’ve used 4seasons with good luck.
Who even Napa buys from and carquest.
If worries pressure check first with like 2psi in a bucket of water. Having a hvac unit “restored” is silly unless you have a 100point show car. Nobody sees it.