Radiator modification

I have a copper core radiator, and I'd like to cut off the original rubber hose inlet/outlets(I think they're 1.5" dia), patch the hole, and add a couple of AN or NPT fittings. What would be the best way to do this? Epoxy? Solder? Braze?
I do have some high-temp adhesive putty(good to 2000deg F) that is supposedly extremely strong, perhaps that would work well? The fittings would be roughly 1". I've relocated my radiator and am now using a remote electric pump, so the old inlet/outlets will have to go, they're gettin in the way.

I'd cut it off and braze a plate over the hole and then putting your fitting on.

you have probably finished this project or had it done at a radiator shop
by now, but i was just browsing the forum, read your post and have some information about radiators. copper core radiators are soldered together, brass tanks soldered to a header at each end of the core, hose fittings and trans coolers soldered to the tank. you should be able to heat the fittings and pull them out. cut a brass patch to cover the hole and solder in place. to attach the an fittings i would solder a threaded brass fiting to the radiator and thread the an fitting in.
when doing repair work on a radiator the solder joints must be super clean and tinned, a little fleck of dirt will be a leak.
be carfeful not to melt the solder out of the tank to header joint.