I like it. Lapel width is just right. One thing I'd do is taper the trousers a bit because it looks wide to be worn with no break, as the model is wearing. The suit doesnt look too small for the model, but the sleeves could be lengthened Â½ inch. Agree the shirt collar isnt the best choice for the suit.
I like the suit and i think with a few minor adjustments it could look very cool. Id lengthen the sleeve by at least an inch and look for a shirt with a collar in keeping with the scale of the lapels. The shirt in the pic is too big for the model - it sags at the neck - and is cut a bit loose for the body too - what it needs is the narrower body that would come with one of those ralph shirts. Ralph Lauren black label does smaller 60's style collar shirts that would fit well with the jackets scale. id hazard that the middle button on the jacket is sitting a little north of the navel - which is ok in a sixties suit but can exaggerate the shrunken look
I think the pants are about a 1 inch too short too although if you shortened them by three inches instead its total tom browne!