I restored a Sears SVA a couple years back, going by Wurpuddy's video as a guide and it came out awesome! Mine was pretty rough when I first got it. I used Magic Eraser to clean up the light, cream colored plastic and it brightened it right up. After sanding and leveling out the gouges in the rubberized paint on the back, I painted over top of that using Dupli-Color universal black (IIRC), which looks like a dark, metallic chocolate Brown instead of black anyway.. Just like the video posted above. Then, I touched up the lettering and clear coated the top shell about half a dozen times. The front gold silk screening was a kind of rubbed off/faded but there's not a whole lot I could do about that. I might try to measure it, replicate the lettering and have a waterslide decal made to go over it someday. Otherwise, this is about as restored/suped up as it gets for this particular console.
Besides the av and rgb mod, I added a super bright blue power on/off LED to it, centered right between the power & reset buttons, then installed a chrome bezel (that are usually used on DIY guitar pedals) around the LED. I had to use a resistor (I forget what value right off hand) to tone down the brightness of the blue light. I should note, this one has a 2609 motherboard in it, the Sears one started acting up. Original 2609 motherboards and bottom shells can be swapped in with a Sears top, just so you know.. In case you have trouble one day or just want to experiment. Anyways, the whole thing came out well in the end and looks really sharp overall. It was a lot of work all in all, but everything is still holding up great and it was totally worth it. It's my daily driver Intellivision.
On yours, I'd see how well it cleans up and go from there before painting, buts that's just me. Try another membrane and keypad from a different model 2609 Intellivision, which are more common than Sears... it should be a direct swap AFAIK. I recommend getting a can of DeOxit D9 contact cleaner and scrub the cart port with a toothbrush or even some rubbing alcohol. Do this with your cartridges as well, using a Qtip. Hopefully this will increase the reliability of everything.
Good luck with it!