I'm sorry man, but Hiruzen is much stronger than Tobirama. That's why he chose Hiruzen to be Hokage when Hiruzen was 14 years old. Because at 14 years old, he already surpassed Tobirama.
lol most likely not as he would look hilarious and that look would not fit him at all.
Imo they are much better example how he could look in prime age:
1)
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2)
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3)
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4)
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5)
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Now it depends if by PRIME Hagoromo you mean before sealing Ten tails in himself or after sealing Ten tails in himself. It is very important hint as we know after sealing Ten tails in yourself your image change a lot. The most known change is white or silver hair etc.
If you mean Pre Juubi Jinchurki Hagoromo Ootsutsuki then my bet is on number #3 or #5
but if you mean Juubi Jinchurki Hagoromo Ootsutsuki then my bet is on number #4 and #2 with more leaning towards number #2.