Though I started with the plans for a MAME cabinet from the Ultimate MAME site, I decided to make some significant adaptations to suit my monitor and control panel plans.
The original plans were for a cathode ray tube monitor of considerable size, actually much, much larger than original arcade game monitors. The monitor I got is a 22" HDTV with a very slender profile. It wouldn't fit the space provided in any dimension; it's a bit too narrow, a lot too short, and very very much shallower, plus it's a 16:9 instead of 4:3 aspect ratio. Hence, I used a bit of trigonometry to reduce the size while keeping the same angle.
The original plans call for building a control panel, but I intend to buy one fully assembled from MAMEroom. It's a fair bit smaller than the original plans, but since it's not built into the plans, I decided to adjust the plans to make the space where the control panel goes a little deeper to better fit it. This might need adjustment after I buy the control panel next month, but for now, the plans will fit the depth and height of the panel. (The width will stick off a bit to either side, but that's typical for MAME cabinets.)
I also reduced the width of the whole cabinet by six inches in order to better fit the width of the monitor. That way, it'll fit the monitor so that there's no space showing on either side. I might put in a bit of a bezel to frame it, but I might just leave it showing as is, since it's a pretty nice front.
Finally, since I don't need clearance for the depth of a cathode ray tube, I was able to make a significant reduction in the cabinet's depth, and simplify the shape: there's no need for the slope at the top rear anymore. The resulting cabinet is about 26" deep instead of 40" deep, but still has gobs of room for the stuff that'll go into it. It's also about 5" shorter, but that's not going to make much difference.
It should fit my components better, be a little simpler to build, take up less space, and still allow plenty of room to access the equipment. I won't start building until after I buy the control panel next month. Though I might dig out one of my old retired computers and try setting up MAME on it to see if they're up to the task, or if I need to buy a cheap computer next time one comes up on Woot.