Well, the only way I know to test ECU's is with a diagnostic kit, but all the ones I know of are OBDII only, but it looks as though your rig isn't OBDII, so I'm not sure of any way to check it. As far as the O2 sensors go, the ECU usually handles checking of them and will give a dummy light if one is faulting. I guessing that you haven't made any major engine mods (cam/crank/etc..) so that shouldn't be the problem. As for my
if it runs fine and only smells rich, just run with it.
Oh, just to me sure, it doesn't smell like rotten eggs does it? B/C if it did, it could just be your cat going bad.
And if your in a smog state, they'll let you know if it's spewing unburnt fuel when they check it.
