Sounds like it will be a very fun car....eventually. Check the compression. If you need to have the valves done, have the existing head rebuilt (as opposed to buying a used or rebuild) by a volvo specific machine shop. It's a lot of work, but it's also an opportunity to gain access to all that old stuff that needs to be cleaned, replaced, tightened... And a freshly rebuilt head will make a huge difference in performance.

But hopefully your compression is good...