Here's some high-level information on cooling, from a *system* perspective:
http://www.4x4wire.com/jeep/tech/engine/cooling/

The radiator you're looking at is a dual-row aluminum radiator, but the cores are deeper than the conventional brass radiator you already know, so I wouldn't wory about it being 'only two core.' You get the added benefit of aluminum's better conductivity.

I can approximate the math, but you should probably verify the actual core area. Let's assume 2.5" thick tanks on either side, so 17in wide a 19in high = 323in^2 which should cool your 260in^3 pretty well, per the default formula of displacement plus a spare 50in^2.

FWIW, I do think that radiator will cool your engine well, if you can feed a reasonable flow through it. A well-fitting fan shroud and fan will also be necessary (IMHO it doesn't matter if it is driven by the 4.3 or an electric motor, if you size the fan appropriately).

Randii