One problem we were trying to solve was finding a heater core that:
- fit in a reasonable sized case
- works with cooling works shroud (so 6" to 6.25" L and H)
- had inlet/outlet that would work with 1/2" ID tubing with minimum modification (cut off, maybe)
- was not made of aluminum
- (optional) was
really cheap
One possible solution was the heater core for the 71 mercury Montego w/air
Here's a picture of the Balkamp (BK 6603012 at napaonline) $42

Looks like maybe there's enough straight run before the bends - so they could be cut off just before the bends and end up with a no-soldering no-goop decent 6x6 radiator (which would be
perfect if I had a beader - but I don't).
Here's a picture of the one from A1 injectors
Note how the tubes angle immediately (no straight run). This is a
drawing, so, was the artist lazy or does this actually not have short straight runs before a bend? I'm guessing that the artist got it right...
Here's the one by 4Seasons
Doesn't look like any usable straight run here, either, does it?
With the drawing of the one at rock auto it's even
harder to tell what the tubes are doing.
Sure wish the local auto parts store had these in stock so I could look at 'em (not a lot of '71 Mercury Montegos on the streets around here, though...) Failing that, I'd guess the one to go with is the Balkamp.