I have a 1954 Singer Model 306W in a cabinet. It has a 3 pin terminal power connection but it didn't have the power cord when I bought it. I found a bunch of numbers on line (W1561910, 190613-19021, BA3-8) and I think one of them is the part number but I have never been able to find the part. If you had one of could get one I would sure like to buy it!
I think you will find a strong market for vintage parts out there. Especially for those of us living in smaller communities and rural areas with no access to reputable sewing machine repair shops. Please let me know if you have this part of if you know where I can find it. Thanks so much and good luck with your venture!