My opinion is that alloy rads only save a bit of weight. They may be a bit more robust than a copper soldered rad, I don't know. I would have Your original recored. If the tank is one of the older flat top variety. Take the bonnet off and go for a drive. You will see the top tank turn into a dome and than when cooled go flat. Ask yourself how many times this can happen before the solder fails on the top tank. I have the rad guy reinforce this tank on the inside. On My +8 Bitsa I am using a copper rad that was replaced by an alloy rad. 10 more years use of this old copper rad and it does the job OK.
