How to upscale the dv 4:3 to dv 16:9 and maintain its quality while scaling
I will say this. Most people who use 4:3 footage in a 16:9 project will only scale up until the clip is even with the top and bottom of the screen. The sides will maintain an even distance from either side of the 16:9 frame. The blank sides will usually be filled in with another layer of video. This background layer will sometimes be graphics and information or even an upscaled, blurred version of the original footage played back in sync. 

Check out this link: https://forums.creativecow.net/thread/8/1153004

I don't believe there is a way to convert your 4:3 footage into 16:9 without loosing any quality. I suggest a hardware upgrade. 

Good Luck, 

ND