Still pondering this one , lupose .
If I were you , I'd avoid trying to 'clean' any areas of your painting (unless you've very experienced with doing so) & I'd also remove the taped-on paper on the reverse of your item , since other clues might exist under it (?) .... the tape appears (from your images only) to be from the 1930's thru 1950's , cellophane type .
As to images matching the exact person in question , without any actual photos of the fellow in question ..... well .... I don't think I'd give up just yet , since -
paintings , by their nature , are based on an artists' interpretation / perception & will often vary from the live model depicted .
I think the fella in the painting is dressed like a rather fashionable 'Dandy' , from the mid to late 1800's .
The landmark in your painting is worth verifying also , IMO .
If you're equiped with the patience , perhaps you could take images from your camera & run 'em through a program , such as 'photoshop' & try manipulating them with greyscale/etc. .... sometimes this will help in areas where a sig is suspected/obscured .
Over & under exposed/lighted images may also lead to clues/answers .