Best way to patch big holes in heater core?

I need to move the inlet/outlet from its current location; perpendicular to the core and put them facing straight out from the end tanks for my application.
I was already planning to replace the oval tubes with barbs.

I did a search and there is plenty of info on whether to JB Weld or solder, but in my situation what would be the best / most reliable way of covering these 2 large holes?
And when I drill the new holes, is there any special precaution I can take to keep metal shavings out of the core?
My heater core is for the '73- caprice. And a picture FWIW.

(I decided on this core based on the suggestions I found in this forum btw. And it's definitely a nice fit with the 2 Stealths although I will only be using 1.)

Have you left a small bit of the original tubes? if you have you can fill them with a circular brass plug (works great)

If you havent you will have to solder a plate over the holes

Ive done the same as you only moving the tubes from the top to the side

Went from this

http://server5.uploadit.org/files/slaterspeed-AstraWFan600.jpg

to This

http://www.hamlesh.com/~publicgallery/albums/public_gallery/corefinished3.jpg

I haven't cut them yet, so I just leave like 1/8" and solder a plug in? Ok I can do that.
What about the shavings? Was it pretty easy to just flush them out?
Thanks for the reply and btw I've come across that picture several times. Your core & shroud are famous lol.

Yeh what i found with mine was the tubes extend inside the core for about 1/4" so i just cut them down to 1/8 long and soldered in a 1/4" plug then filed over the top and used a bit of body filler to make it look clean

You could try and vacume the shavings out first. I just shook out the worst and then flushed it out with some water. If its just dust then it will flush out but try and get the 'chips' out beforehand

You may have seen that pic around here posted by me