Standards ensure that PSU's are made within specifications. So most ATX spec PSUs come in the same size unless you opting for the higher wattage ones that tend to be a bit more longer EPS12V spec (Enermax Galaxy) due to the larger cooling requirement and circuitry. The Lian Li specs should also comment on the size of the PSU bay and to what degree. If not, getting actual sizes of PSU's can be obtained from their respective websites and the rest you can measure for yourself in the case.
On what PSU's to opt for - that's entirly open to debate. I tend to like Enermax for their quality although there might be better options available.
This case is quite restrictive on the size, however, Lian-Li has an accessory which is very handy, its a power supply extender kit. That will get you the extra clearance you require for a decent power supply to fit in this case. You may have to contact them directly, or got to a local specialty computer shop to order the product, as it isn't listed at places like Newegg. http://www.performance-pcs.com/catalog/index.php?main_p...
RGSAUNDERS, thanks for the tip. I know the Lian Li is restrictive, so that's why I asked. I don't quite understand the power supply extender kit -- is this an item that will protrude from the back of my case? How does this work?
Also, is this necessary for a 650w or 750w psu? I don't believe I need 1000+ w. Seems from everything I gather that even if I run 2 4870s in crossfire, I will be OK with a 650w-750w.
The link illustrates the product, what it does is effectively extend the power supply area out the back of the case by another 2 or 3 inches. I found that even so called standard power supplies were a very tight fit, even a 430W modular Antec PS was very tight without the extender.