Do both. Keep driving it and start an engine fund with the hope its fully funded before its needed. Have you noticed any difference in driveability?
I just went thru the same thing. I kept getting more and more traces of potassium in my oil, which is only possible if coolant is getting in. I check all my bases, looked for any possible cases (like Castech heads for instance) but I couldn't find ANY coolant leaks. So I just kept driving it and regularly changing the oil. I got another 4 years, and almost 40k miles out of it from the first reported instance of traces of coolant in my oil. If I had babied it, I probably could have gotten far more life out it. But I drive it live I stole it, and it bit me in the ass because I floored it one day then lost all oil pressure. Long story short, I slipped a cam bearing, go figure.
I ended up getting a crate 5.3 engine from O'Reilly auto parts, and had it installed a few months ago. I have almost 5,000 miles on it and not only is it running great, I'm getting a LOT more fuel mileage than I did with the last engine. I would be lucky to get 13mpg before, now I've been consistently seeing 17-18mpg.