Heater core opions

[jweb]

I have a '51 with the deluxe heater, I replaced the heater core a few years ago. I recently read a post on here about adding a flare to the tube due to the higher pressure newer engines have and the risk of the hoses blowing off.

I took my heater core to a local radiator shop, they added the flare then tested the heater core. They told me it bulges when put under pressure.

So I'm wondering if this is because I'm using a stock style core like this
https://www.classicparts.com/1947-52...info/68%2D221/. Which says not to use higher than a #4 cap.

The local shop wants $280 to "rebuild" my core so it's strong enough for the pressure. My other option is this heater core
http://www.thebrassworks.net/shop/He...895d8211555697.

Looking for any opinions or other options