As I have learned from my teachers in Seoul, and like Wyardly posted, shou production style is older than the 70s, but not anywhere near as common before. The "wet-pile" method used to speed up fermentation is very similar to how Liu Bao is fermented for nearby Guanxi, and was developed off of the Liu Bao method. This production style become more developed and mainstreamed in the 70s. My teacher once had a shou from the 40s. It was taught to me that there were blends as well as pure shou, but the latter was rare. I also heard an independent teashop owner in Malaysia mention that older puerhs are often shou method, borrowed from Liu Bao.
Shou does sometimes have a bad repuation, but it shouldn't. It is not worse than sheng, just different. The flavor is deeper and smoother, and is drinkable immediately, not after many years, but shou is nowhere near as complex as sheng (both in terms of the range of flavor in the cup, as well as in terms of the range of flavors you can find in different teas). But they both are important and are great. I drink more shou than sheng. That said, I agree with Wyardly that there is a limit to how good shou can be, and that sheng can push beyond that, but only older sheng.
As per young sheng, I have actually come to enjoy it now, when I brew it a bit weaker (especially in Yixing clay), and when I think of it as a type of strong green tea, rather than a black tea, as mentioned above, though I prefer boiling water. I feel like you can get the most out of it with boiling water, less leaves, and a flash steep.
As per your options, the sky is the limit! You can find affordable older sheng that isn't so great, but is good enough, as well as learn to drink young sheng, as well as enjoy the whole range of shou. I vote you buy some young sheng, young shou, and then a small amount of old sheng (even just a few samples!) for special occasions.
Side note:I have been asking SOOOO many people their takes on the age at which shou hits its ceiling. I have heard strong assertions not to drink older than 5-year-old shou, and I have heard that it levels out at 30 years, and I have heard that it continues to get better, even after 50!
Finally, I'd say that the idea of high-quality sheng being drunk young and saving low-quality for aging is not as I have learned it. Rather, both are drunk both young and aged, as it is different aspects of different teas that taste good young or that will age well. So, I guess, "good" young tea may or may not age well, and "bad" young tea might even age to be great. Of course very old, wild trees tend to produce better flavors young or old, etc. etc. Storage makes a huge difference too. It is so complex!
Sorry for the marathon post, and good luck!