AIO or sump

[pirate]

Well I started to play around with the tank and I think I will be going with a sump, I don't really want to lose that much of the tank. So now the next question is how big of a hole do I need to drill? I think I want to gowith a herby type drain. How big of a sump should I go for? ( what firs inside of the stand or somehjng else?) how big of a return pump? Should I drill it my self or is there anyone in Calgary that you guys would recomend? It is an older tank if that makes a difference. Or should I do one of those siphone type drain boxs? Any help is good help.
Thanks