Most Volvo tuners start messing with their bricks at higher miles, so don't worry about messing things up with a new part in an old engine. I wouldn't tear into the bottom end of the car because it's too expensive, but you can put new parts on anything if you want. I dropped a K cam (2nd most aggressive camshaft Volvo made) into my '83 245DL at 163,000 miles, and it's still running strong 7,000 miles later.

I suggest you buy the IPD sport exhaust (or make your own for cheaper) and buy a calibrated boost guage to go along with it. The freeflow exhaust will do the most to help your turbo engine to put out the most power. It'll also be the best bang for the buck, though the torque convertor comes close, it just costs a lot more to install. Once the exhaust is in you should have a lot more fun driving.

BTW the spoiler might look nice, but a faster car is a better looking one any day of the week. Save the eye candy until you can blow away most cars. That's what I'm doing with my '83 244ti. Volvos are great sleepers. Good luck with the project.
--
Isaac Babcock - '83 245DL 'Borkie' and '83 244 turbo project