CRT arcade monitor trials and tribulations

[supafraud]

Hello all, so I'll cut right to the chase because I need to explain everything I've done. As the title suggests I have an arcade monitor that I'm trying to setup with my pi. I've tried a few things and have had varying levels of success and am hoping someone can help me straighten a few things out. So the first thing I tried was using gert vga 666 adapter and this guy's config:
http://sommerp.net/doku.php?id=raspberry_pi_arcade

This worked in terms of getting me running 240p but it seems that many games got the graphics chewed up. It was extra bad on vector games, making tempest impossible to play. My guess is that there aren't enough pixels so when it scales to 240p I'm losing portions of the graphics. My CRT is newer, it's from 1997 in a MK3 cabinet and I think it may be capable of a higher res than 240p but I haven't been able to find information on the monitor and I'm not perfectly sure that I was editing the configfile correctly when I was experimenting as my edits often resulted in the monitor just displaying crazy out of sync images. In frustration I purchased a GBS-8100:
http://www.ebay.com/itm/VGA-TO-CGA-CVBS-S-VIDEO-HD-Converter-PC-to-VGA-GBS-8100-Video-Game-Converter/282218068753?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
This converts a vga 1024x768 60hz to a signal (honestly not sure what the exact output is) that the monitor seems to read fine and the scaling is much better which allows me to play tempest etc. This would be acceptable but it's cheap Chinese hardware and there is a lot of noise in the signal and the colors are pretty crushed. The image is also slightly too wide for the screen. I would love to be able to output this straight from the pie through the gert vga 666 but I think I need some help getting it to work from someone that knows more about editing the config files and what the max input for a monitor like mine might be. Thanks in advance!