Well...
Looking at pics of the P160, it looks like you have the following options for radiators.
1. A Chevette core mounted in the top of the case between the upper drive cage and PS. (good compromise)
2. A BIX on the rear 120mm fan. (least favorite)
3. If you'd be willing to scrap the HD cage, it looks like a big dual 120mm fan rad will fit in there. (favorite option)
Of course "fit" has been eye-balled only. It may, or may not.
The most expensive of those options is the BIX at ~$50. The heater cores range from $30-40.
Depending how far over the table Jon bends you for a water block (j/k). You should still have a good chunk of change for a pump. I'd wait to choose a pump until I knew what the flow characteristics of the block.