Damage by improper timing

The timing advance rod broke on my 1987 Force 50hp engine, and in the process of trying to retime the engine I fear that I may have caused damage to the engine. I am very discouraged and though I have yet to use my new timing light to set the timing, I figure after running it for ~2 hours in an effort to set the timing with other methods the engine has suffered severe damage. My question for ya'll is...
1. If I have a low compression reading on one or both cylinders after setting the timing, what are my options in terms of repair? Is it something that I can fix myself, or should I send it to a shop, or should I junk it?
2. At what point does fixing a Force 50 become too much effort when compared to getting a used engine (part costs, part availibility, time, etc)?
3. I have the option of buying a $1300 fully restored Merc 50hp. Should I be concentrating on that more than attempting to fix the Force I have?
Thanks