'72 Merc 120, ignition or valves

[johnnynegaunee]

I'm new to I/O's just bought an old pre-alpha 120hp with points/condenser ignition. This thing pops and backfires some, occationally dies while cruising, but restarts easily at least so far. Plugs and points appear to be new along with the wires too. Does this sound like time for valve work or is this a timing/vacuum advance problem. What should such an old engine show for adequate compression? What is the dwell angle and when should it fire #1, 6 degrees btdc? Is it better to convert the ignition to electronic? Thanks for any input you all can provide.