[68Gold/white]

I like your thinking!
The 68-71 mounts and brackets are sold by several companies, not difficult to obtain.

In addition to the other things mentioned, there was a piece of flat metal, about 3 inches wide, approximately 18 inches long that bolted to the pass side seam area, just behind the pass side exhaust manifold, to act as a heat shield. You may not need it, but it would make it appear as a legit big block pickup, if you desire.
The shift linkages not only boot in different spots, it are also made somewhat differently.
I’d try the factory radiator first. The aftermarket setup will likely require more amps from the alternator. You could easily swap radiators/alternators, later if needed.

Then there’s the issue of the tops of the frame rails. 68 was the first year of the big block. Big block 68’s had the insides of the top rails cut back a couple of inches. I’m just not sure if ALL the 68’s got that modification. There’s plenty of info here, if you can find it. If your frame is not narrowed, it can be done easily. I think all the 69 and newer frames were narrowed on the top, just not sure if all 68’s were (anyone?)

Can’t wait to see results!!!

I hate auto correct!!!