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What's the point of getting another opinion from a different priest?  That puts a layman in the position of adjudicating between the opinions of diferent priests, and so therefore it's meaningless to get different opinions (since you know they're out there), and it would ultimately come down to your own opinion anyway, at the end of the day and in the final analysis.  I believe I recall Bishop Sanborn stating that the faithful could just go with the opinion of the priest they approach and have ready access to ... and are not obliged to go "opinion shopping" until they get one that conforms to their own ideas.  At that point, you might as well just go with what you think, since that's what it'll boil down to anyway if you go from one priest to another getting different opinions.

OP already KNOWS that there are differing opinions about the matter out there.

I should have been clearer. 

Assuming the New Rite of Ordination is doubtful/invalid (which is what I think the OP really thinks), find out what a priest who thinks similarly would think about what to do with past sins confessed to a NO priest.

So far it doesn't sound like the OP has spoken with a priest about what he/she needs to do assuming the NO ordination is doubtful. 

I wasn't referring to getting another opinion on the validity of the rite.

I went through the same questions when I cam over from the NO church to the SSPX.  I did some very sinful acts that I confessed to the NO priest and was literally sick to my stomach when I realized those NO confessions MAY not of been valid.  I asked an old aged SSPX priest about this situation and if I really needed to confess those sins again and he said no.  He said my intent was there and that the next time I received absolution from a traditional priest all those sins along with the ones I currently confessed will have been forgiven even if the NO priest was not valid..    I also must tell you though, that over the years being with the SSPX, I still, gradually re-confessed those sins, not because I felt they weren't forgiven, but because I wanted the act of humility to offerup for things and intentions.  It was not an easy thing to do, but I did it and I felt so go after I did.  Such peace I have now. I to this day re-confess sins from the past for an act of humility and I tell the priest why and they always say that it's good to reflect back on things, not that you dwell on them, but to appreciate and trust the sacraments and realize how far your have come with Gods Grace. I can also tell you that I can now go into the confessional and continue to re-confess anything with such ease.  I think this is grace! I realize no matter how bad the sin, no matter how embarrassing the sin, the priest doesn't care.  The worse it is, the happier they are for you that you are there confessing. So to sum things up, I don't think you need to re-confess, but at the same time, if you do, the grace that comes with reconfessing will give you such peace of mind and soul and even more grace that will help you with future confessions!