www.cokertire.com

They have pretty much anything and everything, in bias or radial. You choose your own cosmetics and size. Using a Canadian vendor eases the import hassles, of course, and the size recommended above seems like a safe bet.

I just went through this in the spring and there is a very long drawn out but somewhat entertaining thread about my project on here CLICK

Basically I switched to 255 and 235 15" and probably should have gone even larger. I thought keeping the car looking stock with stockish 225 14's was a good idea. Too much engine and too much car for those puny tires and wheels. Really wonder why GM ever made these big barges that way. 

BlackCircles.ca is a good Canadian tire retailer with agressive pricing and delivery and service. They have 14's.

Photo shows meaty masculine 255 15's left and 225 14's right. 

I switch wheel size and tires for just under $1,600 so $400 a corner. Tires from Black Circles, Wheels from Summit Racing. 

hawkeye5766 wrote:

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Hankook still makes a 14' tire in a few sizes. They may even still make the 1'ww tire.

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 Yep, they were on my car when I bought it in 2012

My understanding is that a ton of sizes are still available, but demand is low enough that manufacturers only do a smaller batch, then do anther batch when the supply had diminished.

I'd stick with something that is as close to an OD as your original wheel/tire combo;
For me, my original wheel tire combo was a 14x7" steel wheel with F70-14 tires;
So I wanted to find a set of 225/70 R14 tires;
I bought a set last year off kijiji just because it was a smoking deal.

Tire rack, and places like Coker Tire should give you a good idea of what's out there in OEM sizes.
I have understood that BF Goodrich keeps making 14 Radial T/A's purely to accommodate classic cars.

Coker has a few 14" radials

https://www.cokertire.com/tires.html?tire_rim_diameter=2050