There is nothing wrong w/running a intercooler the same size of your radiator.
Unless you are boarder line now from cooling the engine properly.
It might make it run a bit hotter, not by much though IMO.
Your engine will still get cooling air to it.
The factory 6 cyl radiator is small.

I am into doing whatever it takes to cool down the intake temps & a small air to air intercooler does not cut it in my book, but to each his own.
If you run a small or large intercooler I am an advocate of using 100% methanol injection also.

I was data logging my Syclone a few nights ago, about 60 degree F temps outside, intake manifold temps were in the high 80's to 90's, I was running up to 26 psi w/intake manifold temps of 59 degrees F spraying methanol, nice & chilly from the methanol, just the way the engine loves it.
BTW, this was done w/the crappy pump 91 octane gas we have here.
Methanol,,,, it's like running race gas w/out the race gas price.
This the the kit I use: http://mysite.verizon.net/res11pgkr/vehicles/tysyclone.html

You can install a wider radiator in your Nova also.
W/minmal mods my friend installed a radiator for a 75 Camaro.
He was also running a SBC 400 w/11.5:1 compression.

Nothing to it but some cutting of the front core support & a couple simple pieces of sheet metal brackets.

Not saying you need a radiator that big as my friend used, just saying, dont let the small radiator support opening stop you from have a larger radiator or intercooler or both.

MBHD

12 port SDS EFI