Timing for 87 Monte LS with 305?

ok first off i dont know who did the work on this before but here goes.......a friend of mine's monte wont run right......timing was my first guess cuz someone already tried to "fix" it....but the thing is i think this other guy might have gotten rid of the timing marks........help?

between +8-12 with a idel of about 770-900! Atleast to start, it probley will take some tweeking! But if you have a cam or something like that it would be different!