In my opnion the 5.45 chambered AKs sound like a novelty gun to me. They are harder to find parts for, the ammo is much more expensive and harder to find, and you have similar ballistics to the 5.56/.223. Why not just use your ARs (which I am sure you already have since you are looking for AKs now) for that caliber role? Any AK I would get is going to be chambered in 7.62 and will most likely either be a fun gun or a cheap plinker.
That being said, I wouldn't really worry too much about finding AK74 receivers and just look for the AKs. The guy on Gunbroker seems to have legit Ewbanks, but he is price gouging quite a bit (nearly 150% over the manufacturer at a RETAIL levle, who knows what percentage he is making with his dealer discount). I have heard that the Vulcans are universals; they are setup for the 5.54, but a little bit of time with a dremel and they can be used as 7.62s. The ones from DCI (nodakspud) are YUGO only unless otherwise noted. They are made with the frunt trunion bulged specially for the unique front trunion of the Yugos AKs. If you want a Chrome lined barrel, Yugo's don't have them. You could always remove the barrel and press your own in (I have heard of a way to do it with a freeze, emery cloth, and a torch) but it sounds like too much work and too risky for me. The last real receivers to look into are Ewbanks or Global Trades. GTs are out something like 48 days because of special custom serial number runs or something silly, and Ewbanks are basically down to what is currently in stock. Most Ewbanks seem to be shipped with the trunion holes drilled, that means no more work is needed by you to make them accept a particular type of AK parts kit. Of course if your parts kit doesn't line up perfectly with the holes (happens most of the time) then you will need to adjust them so they will. Most people claim it is only off by a hair, but it's still something you need to do. The other option is to not have the trunion holes drilled. This allows you to drill them yourself so your parts kit fits perfectly, but will require that you heat treat the holes yourself (requires a torch). Either way it is up to you.
In all honesty though, which the time that is left (if they are even listed) you should probably concern yourself more with finding one than nit-picking until you have one in your caliber, shape, color, weight, etc. You'll feel really stupid if you don't get one just because they only had Ewbanks and you wanted a Global Trades or something silly.