Thanks for the suggestions so far. Just as twombo, I do want to keep driving this vintage Volvo, and I'd like to get it to the point where it'll replace my modern daily driver.

I think I have all the safety things down as honeychrome suggested I do first. That was actually the approach I was intending. Now that the safety concerns are addressed, it's at this juncture that I'm looking at the engine and driveline reliability improvements. I can improve the reliability by either investing in stock maintenance, or by investing in swapping in beefier performance parts as part of that maintenance, thus, leaving room to evolve. I think this is what it all boils down to...maintain stock or evolve?

I realize that taking her down the performance path will cost more money to reach that end, but I think the final product would make a really nice daily driver. Of course from the responses thus far, stock [and in proper working order] also makes a really nice daily driver. *shrug*