If you're going to add a hood crest, then I personally feel that the lower spot as in this pic from above looks better than too high ....
IMHO the one on the 2 headlight 914-8 above just looks too high - rather than using the line across the high-point of the eyebrows as in dflesburg's pic above (or even a tad lower). You can also use the low point - from the bottom point of the crest to the bottom of the curve of the eyebrows/headlight-lids - rather than the centerline of the badge to the high point of the brow as in the yellow line on the pic above, since that may be easier to find than the badge center (essentially the same location, but possibly an easier measurement technique).
When using the suggested Porsche factory recco'ed position on 911/912/930 noted above as 3.25" (IIRC it's something like 80 or 86 mm in their factory manuals) - I would look visually at the distance on a `64-74 911/912 from the front of the full body-work (not just from the edge of the hood lid - the convenient measuring point), & then compare that to the full distance to the front of the 914's bumper/top-pad front edge - since it's all a continuous line on the 914s.
I think that Porsche designers came up with a 911/912 front hood emblem placement based upon the overall look & setback from the frontal bodywork - then used the measurement from the set hood front edge for that visually best & balanced location aas an easy means for factory workers & dealers/bodyshops to place them.
Our 914s have a different front edge & frontal look than the 64-74 911/912, due to the integrated front bumper (both steel & BUB) which flows continuously in one line - so the visually perfect spot is going to be a different measurement for the front edge of the hood by necessity.
Of course - as you can see from the posts so far - the placement is all in the eye of the beholder, & you'll see them from as low as they can get it to clear the frame on the underside of the front deck lid (hood) to the top back edge of the headlight covers.
So as Mark Epstein said, using a paper or decal temporarily to get "your perfect placement" is a great idea!
Also, I think gandolf's suggestion of using a modern automotive emblem adhesive is a better idea, than drilling 2 new "doors" for the dreaded "tin worm"! I actually was thinking of doing this on my resto too, so I can remove it if needed later on.
Obviously the crest has an attachment for you, so use it - but realize that the crest's up to 73-74 MY were the old school red-orange bands, then they switched over to the red-red bands in 74 on 911s IIRC.
Have Fun with it!
Tom
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