A lot depends on its condition. Normally, if you were looking for a long-term, highly reliable driver, I would advise to go through the bottom end, too. But if you are looking to have a motor for just a few months, and you're not going to put too many thousand miles on it, then there's probably no real problems. It all depends on what you want to achieve. I took your first post at its word - that you are looking to get more out of it for just a little money for the short term only. If you want to build it bullet-proof and get it to last forever, that's another matter.
All the lower end stuff is the same for all motors of that period, including the crank material, rods and pistons - until you get into the Ram Air 4, which had forged pistons and different bearing materials.
If you've got 200K on the lower end and you add a lot of top end horsepower - then, yeah, you might end up with some lower end issues. However, nothing you do will "weaken" what you have there - it will only bring out the weak link in the chain a little faster.
