I don't have an answer for you, but just wanted to show some love.
There is no doubt that there is some residual oil in the system (VIR, evap, condenser), but like you I would question it being 5oz. In its previous life, numerous leaks/recharges probably drained much away. But wow, old compressor only had 1 oz? I'm thinking the whole system was low. It's tough to know without flushing the entire system, but sometimes you play the hand you are dealt. I would feel better to flush even just the condenser.
I would probably trust the 6.72 the compressor manufacturer was supposed to put in it, and add 3oz more after returning your compressor oil that you drained. My reasoning: There are still likely a few ounces in the system, but given that so little came out of the old compressor, I can't imagine much. So I will guess 2 remaining in the system, plus the almost 7 in your compressor, plus the 3 oz add, equals roughly 11-12. A little bit extra oil reduces cooling capacity. Too little kills compressors.
What oil and refrigerant will you be using? Assuming R12, along with compatible oil (mineral or ester)?
Saw you hanging for quite a while with no response, thought I would do my best.
