Does anyone have a tool for Beta 1.7.3 to render worlds to an external file?

I want to develop a large landmass (I'm playing with a mod that restores the infdev-alpha terrain gen) but I need to see the breadth of what I'm working with and I'm not entirely sure just looking at a seed renderer is what I need since I don't know/can't check if the mod I'm using is 1:1 with infdev-early alpha gen.

I've used Overviewer before for release versions, does anyone know if it supports beta? Otherwise what tools do people use? Thanks