This is similar to my project. There are a few things you should be aware of before you start this...
First, what type of chiller is it? Peltier core? Bath? Phase-change (ie water-fountain)? If you are using a TEC based chiller you should *really* be careful of where the exhaust for all that heat will go... if it's going anywhere near other 'cooling' components, you will have seriously decreased results. The reason you put the rad in front of the chiller is to bring the water-temp as close to ambient as possible. If the ambient temp around the radiator is 10° higher than the 'actual' room temp, you are defeating its purpose simply by having poor airflow for your TEC chiller.
That's currently the problem I've been running into... to get the best performance, I have to route my outgoing air 'outside' to keep from heating my room up so much. My chiller has 10 TECs though... that's a lot of heat.
You should also be concerned with waterflow through the chiller. I'm not sure if the rule applies for *all* chillers, but low-flow is sort of 'critical' for TEC chillers. The longer the water stays in the bath/core, the cooler it will get. If it's just rushing through the channels at 1000gph (and little pressure), the cooling won't be as beneficial. I'm not done testing the exact numbers, but the difference between 1/8" barbs and 1/2" barbs on my chiller seems to be dramatic.
The main problem I'm seeing is your water-block choice. The mcw5000-a makes a great peltier block because it is an incredibly high-flow block (if I'm thinking of the right block). Other blocks such as the whitewater or cascade need pressure more than they need high flow. If you are combining a chiller that works best with low flow with a waterblock that is at home in a high flow system, you might run into lower than anticipated results.
When it all boils (pun!) down to it, you are going to be doing a LOT of experimenting. I have the luxury of trying out several pumps, rads and tube/barb sizes. I'm figuring out what works best for MY installation, but I can't answer general questions for ALL installations. BillA would be a good source for something like that =p. I guess the key thing is to keep changing things around until you get your ideal setup.